JP2005329182A - Temperature control device of showcase - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transmit serial data to a temperature display part from a temperature control part without a clock signal in a temperature control device of a showcase, in which the temperature control part and the temperature display part are connected with a signal wire. <P>SOLUTION: A first microcomputer 11 of the temperature control part 1 outputs serial data having a minus sign bit expressing a positive or negative sign, a first display data string expressing a figure in the ten's place, a predetermined first fixed data string, a second display data string expressing a figure in the one's place, and a predetermined second fixed data string. A second microcomputer 31 of the temperature display part 3 detects the first fixed data string and the second fixed data string from the serial data outputted from the temperature control part 1, detects the minus sign bit, the first display data string and the second display data string according to the array of the serial data, and displays the interior temperature in a display circuit 32. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a temperature control device for a showcase in which a temperature control unit and a temperature display unit are connected by a signal line, and in particular, it does not require a clock signal and can be communicated with only one signal line for serial data. The present invention relates to a case temperature control device.

  For example, when controlling the display of frozen and refrigerated showcases where food is displayed and sold, the temperature inside the cabinet is detected, the set temperature is compared, and the temperature controller that controls the compressor, and the cabinet temperature and operating status are displayed. A temperature control device including a temperature display unit is used. Generally, the temperature control unit is installed in a storage room where a compressor or the like provided in the lower part of the showcase is installed, and the temperature display unit is set in the showcase unit away from the storage room. The units are connected by a signal line, and the temperature display unit displays the internal temperature and the operation state by a signal transmitted from the temperature control unit.

  That is, in this type of temperature control device, as shown in FIG. 6, the temperature control unit 61 and the temperature display unit 63 are connected by the lead wire 65 and used.

  The temperature control unit 61 is installed, for example, in the storage compartment of the showcase, detects the temperature inside the showcase, compares it with the set temperature, controls the compressor installed in the same storage room, and displays display data of the internal temperature. Is converted into serial data and output together with a clock signal.

  This temperature control unit 61 displays the CPU 611 for controlling the display temperature of the showcase and transmitting display data, the ROM 612 for storing the program, the RAM 613 for storing data such as the set temperature, and the internal temperature and the set temperature. Display unit 614, an A / D conversion unit 615 that converts the internal temperature of an analog signal detected by a temperature detection circuit including a thermistor, a resistor, and the like into a digital signal, a set temperature set by a button, and the like And an I / O circuit 616 for outputting a compressor control signal.

  The temperature display unit 63 is provided, for example, on the front panel surface of the showcase, and has a function of capturing serial data at the timing when the clock signal is input and converting it into parallel data, and holding the current at the timing when the clock signal is input Display temperature control data is displayed on the display, and when the clock signal is not input, it has a display data control function for capturing and holding the converted parallel data

  The temperature display unit 63 is controlled by a shift register circuit 631 that converts serial data into parallel data, a latch circuit 632 that controls display output, a resistor 633 and a capacitor 634 that determine control conditions for the latch circuit, and a latch circuit. Display 635 for displaying the measured temperature and the like. The display 635 includes, for example, two 7-segment numeric display elements and one 1-segment minus display element.

  In this temperature display device, display data is transmitted between the temperature control unit 61 and the temperature display unit 63 by using a clock synchronous serial communication method. When this clock synchronous serial communication method is adopted, in order to transmit the serial data of the display temperature from the temperature control unit 61 to the temperature display unit 63, it is different from the serial data in order to obtain the timing for taking in the serial data. A clock signal is required, and the temperature control unit 61 and the temperature display unit 63 must be connected by a serial data transmission lead wire 65a and a clock signal transmission lead wire 65b. Two lead wires are required.

  Moreover, in the showcase, when wiring the lead wire connecting the temperature control unit 61 installed at the lower part of the showcase and the temperature display unit 63 installed in the showcase unit, the food display unit in the showcase cabinet For example, wiring is made through hollow support columns at the four corners of the case so that the space can be used effectively and the aesthetic appearance is not impaired. Therefore, if the number of lead wires connecting the temperature control unit 61 and the temperature display unit 63 is large, the space cannot be used effectively, and wiring work becomes difficult and time-consuming.

When the temperature control unit 61 installed in the storage room and the temperature display unit 63 installed on the front panel surface of the showcase unit away from the storage room are connected by the lead wire 65, the lead wire generally has a length of about 3 m. As the number of lead wires increases, the cost increases accordingly.
Japanese Patent No. 3156898

  In view of the above problems, the present invention obtains serial data capture timing when connecting the temperature control unit and the temperature display unit with lead wires and transmitting serial data of the display temperature from the temperature control unit to the temperature display unit. The number of lead wires connecting the temperature control unit and the temperature display unit is reduced by making it possible to transmit serial data of the display temperature with only one serial data lead wire without the need for a clock signal for An object of the present invention is to provide a temperature control device for a showcase that makes it possible to make effective use of space and simplify wiring work.

  Furthermore, the present invention reduces the cost of lead wires by reducing the number of long lead wires that connect the temperature control unit of the storage room installed remotely and the temperature display unit of the showcase unit. An object is to provide a temperature control device for a case.

  In addition, an object of the present invention is to provide a temperature control device for a showcase that is highly resistant to noise even when communication is performed by connecting a temperature control unit and a temperature display unit with a long lead wire.

  In order to solve the above problems, the present invention includes a temperature control unit that controls the temperature inside the showcase, and a temperature display unit that displays the temperature inside the showcase, the temperature control unit and the temperature display. In the temperature control device for a showcase, which is connected with a signal line, the temperature control unit includes a first microcomputer, temperature detection means for detecting the temperature inside the showcase, compressor control means, A signal output means connected to the signal line, and the first microcomputer compares the internal temperature detected by the temperature detection means with a set temperature to control the compressor control means, and The temperature displayed on the temperature display unit is converted into a display data string, serial data having the display data string and a preset fixed data string is generated, and the serial data is generated. Is output to the signal output means, and the serial data is output to the temperature display unit via the signal line. The temperature display unit is connected to the second microcomputer and the signal line. The second microcomputer has a signal input means and a temperature display means, and the second microcomputer inputs the serial data from the signal input means and detects the fixed data string and the display data string from the serial data. The signal corresponding to the display data string is output to the temperature display means so as to display the temperature.

  According to the present invention, in the temperature control device of the showcase described above, the serial data includes a minus bit that represents a positive or negative sign of a temperature to be displayed and first display data that represents a tenth digit of the temperature to be displayed. A second display data string representing a column and a number of one's place, and the predetermined first fixed data string and second fixed data string are provided.

  According to the present invention, in the temperature control device for a showcase, the first fixed data string and the second fixed data string are arranged differently from the first display data string and the second display data string. I made it.

  According to the present invention, in the temperature control device of the showcase, the first fixed data string and the second fixed data string have a data length of 6 bits, and the first fixed data string has an array of “000101”. Yes, the second fixed data string has an arrangement of “110010”, or the first fixed data string has an arrangement of “110010”, and the second fixed data string has “000101”. It was made to be the arrangement of.

  According to the present invention, in the temperature control device of the showcase, the first display data string and the second display data string have a data length of 7 bits.

  According to the present invention, in the temperature control device of the showcase, the arrangement of the serial data includes a first start bit, the minus bit, the first display data string, the first fixed data string, and a first stop. A bit, a second start bit, the second display data string, the second fixed data string, and a second stop bit are arranged in this order.

  According to the present invention, in the temperature control device of the showcase, the data displayed on the temperature display unit is a number, a letter, or a symbol, based on the serial data output from the temperature control unit.

  According to the present invention, in the temperature control device for the showcase, the second microcomputer detects the serial data every predetermined time, and when the fixed data string cannot be detected a predetermined number of times, The predetermined time was changed.

  According to the present invention, in the temperature control device of the showcase, when the second microcomputer detects the serial data, the second microcomputer detects each bit of the serial data a plurality of times, and determines the number of detections for each detected level. In addition to counting, a level with a large number of detections is used as bit data of the bit.

  According to the present invention, in the temperature control device for the showcase, the second microcomputer has a predetermined data string table, and the data string table is compared with the detected display data string, Only when the display data string matches any one of the data string tables, a signal corresponding to the display data string is output to the temperature display means to display the temperature.

  According to the present invention, in the temperature control device of the showcase, the first microcomputer outputs the serial data having the same display data string a plurality of times continuously, and the second microcomputer inputs a plurality of input data. Only when all of the display data strings in the serial data coincide with each other, a signal corresponding to the display data string is output to the temperature display means to display the temperature.

  According to the present invention, in the temperature control device for the showcase, the second microcomputer has a predetermined data string table, and the data string table is compared with the detected display data string, When the display data string does not match any one data string in the data string table a predetermined number of times, the predetermined time for detecting the serial data is changed.

  According to the present invention, the first microcomputer of the temperature control unit generates serial data having a display data string indicating the display temperature and a predetermined fixed data string, and the serial data is stored in the temperature display unit. At the same time, the second microcomputer of the temperature display unit first reads the fixed data string determined from the input serial data, then reads the display data string, and according to the display data string Since the temperature can be displayed, a clock signal for obtaining the timing for reading the serial data is not required, and the display temperature can be transmitted with only one lead wire for serial data transmission. The number of lead wires for connecting can be reduced. Therefore, the space of the showcase can be used effectively, and wiring work is simple and easy. Furthermore, since the number of long lead wires that connect the temperature control unit of the storage room and the temperature display unit of the showcase unit that are installed apart from each other can be reduced, the cost of the lead wires can be reduced.

  Further, according to the present invention, the serial data is arranged in such a manner that the first start bit, the minus bit representing the positive or negative sign of the display temperature, and the first display data string representing the tenth digit of the temperature to be displayed. , A first fixed data string indicating an intermediate point of serial data, a first stop bit, a second start bit, a second display data string representing a digit of the displayed temperature, and an end point of the serial data Since the first fixed data string and the second fixed data string are detected, the data between them is detected in accordance with the serial data arrangement. By reading the columns, it is possible to detect the display data columns at the 10th and 1st positions of the temperature to be displayed, and the temperature display according to this display data sequence can be performed. There is no need for a clock signal to obtain the timing to read data, the display temperature can be transmitted with only one lead wire for serial data transmission, and the number of lead wires connecting the temperature control unit and the temperature display unit is reduced. Can do. Therefore, the space of the showcase can be used effectively, and the wiring work is simple and easy. Furthermore, since the long lead wire which connects the temperature control part of the storage room installed away and the temperature display part of the showcase part can be reduced, the cost of the lead wire can be reduced.

  Furthermore, according to the present invention, the second microcomputer of the temperature display unit converts serial data output at predetermined intervals from the first microcomputer of the temperature control unit at the same predetermined intervals. If the fixed data string cannot be detected from the serial data a predetermined number of times, the second microcomputer changes the predetermined time for detecting the serial data. Even if the operation clocks of the two microcomputers do not match, a fixed data string can be detected and a display data string can be detected, so that a clock signal for obtaining the timing for reading serial data is unnecessary. Display temperature can be transmitted with only one lead wire for serial data transmission. It is possible to reduce the number of leads connecting the degree controller and temperature display unit.

  In addition, according to the present invention, the second microcomputer of the temperature display unit detects each bit of the serial data a plurality of times, counts the number of detections for each detected level, and sets the level with the highest number of detections. Because bit data is used, even if the temperature control unit and temperature display unit are connected with a long lead wire for communication, erroneous display due to the effect of noise can be prevented, and communication with high noise tolerance can be achieved. it can.

  Further, according to the present invention, the second microcomputer of the temperature display unit has a table of display data strings that can be displayed in advance, and compares the detected display data string with the display data string of the table. Because the temperature corresponding to the display data string is displayed only when it matches one of the data strings, even if communication is performed by connecting the temperature control unit and the temperature display unit with a long lead wire, an error due to the influence of noise will occur. Display and the like can be prevented, and communication with high noise tolerance can be made possible.

  Furthermore, according to the present invention, the first microcomputer of the temperature control unit outputs serial data having the same display data string a plurality of times in succession, and the second microcomputer of the temperature display unit inputs a plurality of input data. Since the temperature corresponding to the display data string is displayed only when all the display data of the serial data match, even if communication is performed by connecting the temperature control unit and the temperature display unit with a long lead wire, the effect of noise Can prevent erroneous display, and enables communication with high noise tolerance.

  In addition, according to the present invention, the second microcomputer of the temperature display unit has a table of display data strings that can be displayed in advance, and compares the detected display data string with the display data string of the table. When the second microcomputer does not coincide with any one data string for a predetermined number of times, the second microcomputer detects a predetermined time for detecting the serial data, so that the operation clock of the first microcomputer and the second microcomputer are changed. Even if the operation clocks do not match, the display data string can be detected, and even if communication is performed by connecting the temperature control unit and temperature display unit with a long lead wire, erroneous display due to the influence of noise, etc. Can be prevented, and communication with high noise tolerance can be achieved.

  Hereinafter, a temperature control device for a showcase according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram for explaining an outline of a circuit configuration when a temperature control device for a showcase according to the present invention is applied to a freezer / refrigerated showcase.

  The temperature control device for a showcase according to the present invention is configured by connecting a temperature control unit 1 and a temperature display unit 3 with a lead wire 5 as a signal line.

  The temperature control unit 1 is installed in, for example, a storage room below the showcase, compares the internal temperature detected by the thermistor 7 installed in the showcase storage with the set temperature, and the compressor 9 installed in the same storage room. To control the temperature inside the showcase.

  The temperature control unit 1 is composed of a resistor or the like, and includes a resistance circuit 12 as temperature detecting means for converting the temperature detected by the thermistor 7 into an analog voltage, a switch circuit 13 for inputting a set temperature, a minus display LED, It is composed of a 7-segment LED, etc., and is connected to a display circuit 14 for displaying a set temperature and an internal temperature, a relay circuit 15 as a compressor control means, and a lead wire 5 for outputting serial data to the temperature display unit 3. The signal output circuit 16 as a signal output means composed of a transistor or the like and the analog voltage from the resistor circuit 12 are input to detect the internal temperature, and the detected internal temperature is displayed on the display circuit 14. At the same time, the detected internal temperature is compared with the set temperature input from the switch circuit 13, and the compressor is connected via the relay circuit 15. Controls, and has a first microcomputer 11 for outputting the internal temperature to be displayed on temperature display unit 3 to the signal output circuit 16 as serial data.

  Here, the first microcomputer 11 includes a ROM 112 that stores a program and predetermined data, a RAM 113 that stores variables such as an input set temperature, an input of a set temperature from the switch circuit 13, and a display. An I / O circuit 114 that outputs display data to the circuit 14, a compressor control signal to the relay circuit 15, and serial data to the signal output circuit 16, and an analog voltage input from the resistor circuit 12 A / D converter 115 for converting the data into digital data, a timer 116 for measuring time, the internal temperature input from A / D converter 115 according to the program and data stored in ROM 112, and RAM 113 The compressor control signal for controlling the relay circuit 15 is compared with the set temperature stored in the The CPU 11 generates serial data representing the temperature displayed on the temperature display unit 3 and outputs the serial data to the signal output circuit 16 bit by bit for every measurement time of the timer 116. .

  The temperature display unit 3 is installed on the front panel surface of the showcase, for example, and displays the internal temperature and the operating state with numbers, characters or symbols based on serial data transmitted from the temperature control unit 1 through the lead wire 5. To do.

  The temperature display unit 3 is connected to a lead wire 5 that is a signal line, and includes a signal input circuit 33 as a signal input unit configured by a transistor that inputs serial data from the temperature control unit 1, a minus display LED 321, It consists of two-digit 7-segment LEDs 322 and 323, resistors, etc., and inputs the serial data from the display circuit 32 as a temperature display means for displaying the internal temperature and operation state with numbers, characters or symbols, and the signal input circuit 33 Then, a display data string included in the serial data is detected, and a signal corresponding to the display data string is output to the display circuit 32 by the dynamic drive method, and the internal temperature and the operating state are displayed in numbers, letters or symbols. And a second microcomputer 31.

  The second microcomputer 31 includes a ROM 311 for storing programs and predetermined data, a RAM 312 for storing variables and data such as numbers, characters or symbols to be displayed, and serial data input from the signal input circuit 33. , An I / O circuit 314 for outputting a display signal to the display circuit 32, a timer 313 for measuring time, and a signal input circuit for each measurement time of the timer 313 in accordance with a program and data stored in the ROM 311 In addition to detecting the serial data input from 33, the display data string included in the detected serial data is read, and a signal corresponding to the display data string is output to the I / O circuit 314. It has a CPU 315 that displays numbers, letters, or symbols representing temperature and operating status. To have.

  In the temperature control device for a showcase having such a configuration, the temperature control unit 1 converts the temperature input of the thermistor 7 attached in the showcase cabinet into an analog voltage by the resistor circuit 12, and the first microcomputer 11. To enter. The first microcomputer 11 converts the analog voltage into digital data by the A / D converter 115 and inputs the digital data to the CPU 111 to obtain the temperature inside the showcase and store it in the RAM 113. The CPU 111 The set temperature input from the switch circuit 13 and stored in the RAM 113 is compared with the internal temperature, and a compressor control signal is output to the relay circuit 15 via the I / O circuit 114, so that the compressor 9 is turned on / off. OFF control is performed to control the temperature in the showcase. Further, the CPU 111 outputs a display signal of the detected internal temperature to the display circuit 14 via the I / O circuit 114 and displays the internal temperature on the display circuit 14. At the same time, the CPU 111 follows the program stored in the ROM 112 to indicate the detected internal temperature as a minus bit representing a positive or negative sign, a first display data string representing a tenth digit, and a first digit. The CPU 111 converts these data strings, a first fixed data string that represents a predetermined intermediate point of serial data, and the end point of the serial data. Serial data composed of a second fixed data string to be represented, a start bit, and a stop bit is generated, and this serial data is converted into I / O for each predetermined time based on the measurement time of the timer 116. The internal temperature output to the signal output circuit 16 through the O circuit 114 and displayed on the temperature display circuit 3 is output as serial data through the lead wire 5.

  In the temperature display unit 3, the serial data output from the temperature control unit 1 is input to the second microcomputer 31 via the lead wire 5 and the signal input circuit 33. In the second microcomputer 31, the CPU 315 detects the serial data input from the I / O circuit 314 at predetermined intervals based on the measurement time of the timer 313 and stores it in the RAM 312. The CPU 315 stores the serial data in the RAM 312. A first fixed data string representing an intermediate point of predetermined serial data stored in the ROM 311 and a second fixed data string representing an end point of the serial data string are stored in the stored serial data string. Based on the sequence of serial data detected from that position, a minus bit representing a positive or negative sign, a first display data string representing a 10th digit, and a second representing a 1st digit The display data string is detected, and a signal corresponding to these data is output to the display circuit 32 via the I / O circuit 314, and the display circuit 32 is output. Negative display LED321 and 2-digit 7-segment LED322 and 323, and controlled by the dynamic drive system, displays the inside temperature.

  At this time, the CPU 315 selects the first fixed data string representing the intermediate point of the predetermined serial data stored in the ROM 311 from the serial data stored in the RAM 312 and the end point of the serial data. If the fixed data string of 2 cannot be detected, the CPU 315 changes the measurement time of the timer 313, changes the predetermined time for detecting the serial data input from the I / O circuit 314, and detects the serial data. Change the interval.

  An example of an arrangement of serial data in the showcase temperature control apparatus of the present invention will be described with reference to FIG. The serial data is generated by the CPU 111 based on the measurement time of the timer 116 included in the first microcomputer 11 in the temperature control unit 1. For example, data of 31 bits per cycle (93 mSec) in which 1 bit is 3 mSec. The 31-bit serial data is repeatedly output from the temperature control unit 1. The serial data includes a Lo-level first start bit Sta1, a minus bit Dm indicating a positive or negative sign of the internal temperature, and a 7-bit first display data string indicating a tenth digit of the internal temperature. D16 to D10, a predetermined 6-bit first fixed data string “000101” representing an intermediate point of serial data, a Hi-level first stop bit Sto1, a Lo-level second start bit Sta2, and the interior A 7-bit second display data string D06 to D00 representing the number of the ones of the temperature, a predetermined 6-bit second fixed data string “110010” representing the end point of the serial data, and the Hi level first 2 stop bits Sto2.

  Here, using the display data string table shown in FIG. 3, the first display data string and the second display data string of the serial data in the present invention, the 7 segment LED 322 of the display circuit 32 in the temperature display unit 3, and The relationship between the number of the internal temperature displayed in H.323 and the characters and symbols representing the operation state will be described. For example, the number representing the internal temperature displayed on the 7-segment LED 322 or 323 is “0-9”, and the characters and symbols representing the operation state are “−”, “H”, “I”, “L”. , “O”, “d”, “F”, etc., the display data string corresponding to these numbers, letters or symbols is stored in advance in the ROM 112 of the first microcomputer 11 in the temperature controller 1 as a table. The CPU 111 stores the number corresponding to the number of the internal temperature displayed on the 7-segment LEDs 322 and 323 of the display circuit 32 in the temperature display unit 3 or the character or number indicating the operation state when generating the serial data. The data strings are read from the display data string table of the ROM 112, and are respectively used as the first display data string and the second display data string. To generate the real data. Here, a to g of the display data string in the table correspond to the respective segments a to g of the 7-segment LED shown in the table as they are, “1” means that the segment is turned on, and “0” means that the segment is turned off. ing.

  As apparent from FIGS. 2 and 3, in the present invention, the first fixed data string “000101” representing the intermediate point of the serial data shown in FIG. 2 and the second fixed data string “representing the end point of the serial data” in the present invention. 110010 "has a different arrangement from the display data string of the display data string table shown in FIG. 3, and therefore, the first display data string, the second display data string, the first fixed data string, and the second fixed data string The second microcomputer 31 in the temperature display unit 3 that detects serial data generated from the fixed data string includes the first display data string, the 23rd display data string, the first fixed data string, and the second data string. A fixed data string can be easily identified.

  The serial data generation and output processing in the first microcomputer 11 of the temperature control unit 1 will be described with reference to FIG. In the first microcomputer 11, the RAM 113 includes a serial data output counter D, an output bit counter B, minus bit data representing a positive or negative sign, a first display data string, and a second display data string. Is stored, and the generated serial data is output from the serial data output port Ps in the I / O circuit 114. When the first microcomputer 11 executes the program stored in the ROM 112, the serial data output counter D, the output bit counter B, and the display data memory M are cleared to “0” by the initialization program. 4 is a timer interrupt program stored in the ROM 112, and is executed every 3 mSec based on the measurement time of the timer 116. In the first microcomputer 11 shown in FIG.

  When the program stored in the ROM 112 is started in the first microcomputer 11, first, the initialization program is executed, and the serial data output counter D, the output bit counter B, and the display data memory M secured in the RAM 113 are stored in the first microcomputer 11. After being cleared to “0”, the internal temperature input from the thermistor 7 to the CPU 111 via the A / D converter 115 and the set temperature input from the switch circuit 13 to the CPU 111 via the I / O circuit 114. And the CPU 111 controls the relay circuit 15 via the I / O circuit 114, and a temperature control program for turning the compressor 9 on and off is executed and detected via the I / O circuit 114. A signal corresponding to the internal temperature is output to the display circuit 14, and 7 segments of the display circuit 14 are output. Such as the display program for displaying the-compartment temperature in the ED is executed.

  At the same time, the first microcomputer 11 starts the timer 116 in the initialization program, and the timer interrupt program is executed every 3 mSec based on the measurement time of the timer 116, as shown in FIG. Serial data generation and output processing is executed. When this timer interrupt program is executed, it is first determined whether or not the output bit counter B is “0” (first start bit Sta1) (S1). When it is the first start bit Sta1, it is determined whether the serial data output counter D is “0” (S2). When the serial data output counter D is “0” in step S2, since it is the first serial data output, the minus bit data which is the display data of the internal temperature of the display data memory M, the first display data string, The second display data string is updated to the latest display data (S3). When the serial data output counter D is not “0” in step S2, since it is the second serial data output, the same temperature display data as the first time is output, so the display data in the display data memory M is not updated. Next, since it is the first start bit Sta1, the serial data output port Ps is set to “0” (Lo) (S4). Then, it is determined whether or not the output bit counter B is “30”, that is, whether or not the output of all the bits in one cycle of the serial data has been completed (S5). If the output bit counter B is not “30”, all the bits of one serial data cycle have not been output yet, so the output bit counter B is incremented by “1” (S6). The process ends. If the output bit counter B is “30” in step S5, the output of all bits (31 bits) in one cycle of the serial data is completed, so the output bit counter B is cleared to “0” and initialized (S7). ). Next, it is determined whether the serial data for one cycle after the output is the first serial data output (serial data output counter D = 0) or the second serial data output (serial data output counter D = 1). Determination is made (S8), and if the serial data output counter D = 0, the first serial data output has been completed and the second serial data is output in the next processing, so the serial data output counter D is set to “1”. (S9), if the serial data output counter D is not 0, the serial data output counter D is 1 and the second serial data output is completed. The serial data output counter D is reset to “0” (S10), and the first timer interrupt program The process is terminated.

  Thereafter, when 3 mSec elapses, the second timer interrupt program is executed and the determination of step S1 is executed. However, since the output bit counter B is no longer “0”, the output bit counter B is “1”. Is determined, that is, whether the output timing is a minus bit or not (S11). Here, when the output bit counter B is “1”, it is determined whether or not the minus display LED is turned on with reference to the minus bit data in the display data memory M (S12), and when the minus display LED is turned on. The serial data output port Ps is set to “1” (S13), and when the minus display LED is not turned on, the serial data output port Ps is set to “0” (S14). Next, the process proceeds to step S5, in which it is determined whether or not the output bit counter B is “30”, that is, whether or not the output of all the bits of one serial data cycle has been completed. If not, all the bits in one cycle of serial data have not been output yet, so the output bit counter B is incremented by “1” (S6), and the processing of the second timer interrupt program is terminated.

  Thereafter, when 3 mSec has elapsed and the third timer interrupt program is executed, the determinations of step S1 and step S11 are executed, but the output bit counter B is no longer “0” or “1”. Therefore, it is determined whether or not the output bit counter B is “2”, that is, whether or not it is the output timing of the g bit of the first display data string representing the 10th digit (S15). When the output bit counter B is “2”, the g bit of the first display data string stored in the display data memory M is referred to and it is determined whether or not the g bit is “1”. When the g bit is “1” (S16), the serial data output port Ps is set to “1” (S17). When the g bit is not “1”, the serial data output port Ps is set to “0”. Set (S18). In step S5, it is determined whether or not the output bit counter B is “30”, that is, whether or not the output of all the bits of one cycle of the serial data has been completed. If not, all bits in one cycle of serial data have not been output yet, so the output bit counter B is incremented by “1” (S6), and the third timer interrupt program processing is terminated.

  After this, from the processing of the fourth timer interrupt program after 3 mSec to the processing of the ninth timer interrupt program, the same processing as the processing of steps S15 to S18 is executed every 3 mSec, thereby displaying the display data. Reference is made sequentially to the f to a bits of the first display data string representing the tenth digit stored in the memory M, and the serial data output port Ps is sequentially set in accordance with this to display the tenth digit to be displayed. Are sequentially output from the serial data output port Ps at intervals of 3 mSec.

  Further, when the tenth timer interrupt occurs after 3 mSec, the timer interrupt program starts output processing of the first fixed data string representing the intermediate point of the serial data. That is, it is determined whether or not the content of the output bit counter B is “9” (S19). When the output bit counter B is “9”, the serial data output port Ps is set to “0” ( S20), Steps S5 and S6 are executed, the output bit counter B is incremented by "1", and the tenth timer interrupt program processing is terminated.

  Thereafter, from the processing of the eleventh timer interrupt program after 3 mSec to the processing of the fifteenth timer interrupt program, the same processing as the processing of step S19 and step S20 is executed every 3 mSec, so that the serial data Each bit of the first fixed data string representing the intermediate point is sequentially set to the serial data output port Ps, and the first fixed data string “000101” representing the intermediate point of the serial data is serialized at intervals of 3 mSec. Output from the data output port Ps (steps S21 to S30).

  Next, when the 16th timer interrupt occurs, the first interrupt bit Sto1 is output by the timer interrupt program. That is, it is determined whether or not the content of the output bit counter B is “15” (S31). When the output bit counter B is “15”, the output timing of the first stop bit Sto1 is the serial data output. The port Ps is set to “1” (Hi) (S32), steps S5 and S6 are executed, the output bit counter B is incremented by “1”, and the 16th timer interrupt program processing is completed.

  Thereafter, when the 17th timer interrupt occurs, the timer interrupt program performs the output process of the second start bit Sta2. That is, it is determined whether or not the content of the output bit counter B is “16” (S33). When the output bit counter B is “16”, the output timing of the second start bit Sta2 is the serial data output. The port Ps is set to “0” (Lo) (S34), steps S5 and S6 are executed, the output bit counter B is incremented by “1”, and the 17th timer interrupt program processing is completed.

  Next, when the 18th timer interrupt processing occurs, the timer interrupt program determines whether or not the output bit counter B is “17”, that is, the output of the g bit of the second display data string indicating the number of the 1's place. It is determined whether it is timing (S35). Here, when the output bit counter B is “17”, the g bit of the second display data string stored in the display data memory M is referred to and it is determined whether or not this g bit is “1”. When the g bit is “1” (S36), the serial data output port Ps is set to “1” (S37). When the g bit is not “1”, the serial data output port Ps is set to “0”. After setting (S38), steps S5 and S6 are executed, the output bit counter B is incremented by "1", and the 18th timer interrupt program processing is terminated.

  After this, from the 19th timer interrupt program processing after 3 mSec to the 24th timer interrupt program processing, the display data is displayed by executing the same processing as the processing of step S35 to step S38 every 3 mSec. By sequentially referring to the f to a bits of the second display data string representing the one's digit stored in the memory M, the serial data output port Ps is sequentially set according to this, and the one's digit to be displayed is displayed. The second display data string to be expressed is sequentially output from the serial data output port Ps at intervals of 3 mSec.

  Further, when the 25th timer interrupt occurs after 3 mSec, the timer interrupt program starts the output processing of the second fixed data string indicating the end point of the serial data. That is, it is determined whether or not the content of the output bit counter B is “24” (S39). When the output bit counter B is “24”, the serial data output port Ps is set to “1” ( S40), Steps S5 and S6 are executed, the output bit counter B is incremented by "1", and the 25th timer interrupt program processing is terminated.

  After this, from the process of the 26th timer interrupt program after 3 mSec to the process of the 30th timer interrupt program, the same process as the process of step S39 and step S40 is executed every 3 mSec, thereby obtaining serial data. Each bit of the second fixed data string indicating the end point of the serial data is sequentially set to the serial data output port Ps, and the second fixed data string “110010” indicating the end point of the serial data is serialized at intervals of 3 mSec. Output from the data output port Ps (steps S41 to S50).

  Next, when the 31st timer interruption occurs, the second interruption bit Sto2 is output by the timer interruption program. That is, it is determined whether or not the content of the output bit counter B is “30” (S51). When the content of the output bit counter B is “30”, the output timing of the second stop bit Sto2 is the serial timing. The data output port Ps is set to “1” (Hi) (S52), and the process proceeds to step S5. When the output bit counter B is “30”, the output bit counter B is cleared to “0”. (S7) Next, it is determined whether or not the serial data output counter D is “0” (S8). When the serial data output counter D is “0”, it becomes the second serial data from the next processing. The serial data output counter D is set to “1” (S9), and the 31st timer interrupt program processing is terminated. Thereby, the output of one cycle of serial data is completed.

  In the above processing, when the output bit counter B is “0” (first start bit Sta1), the serial data output port Ps is set to “0”, and the output bit counter B is set to “9, 10, 11, 12”. , 13, 14, “(first fixed data string representing the intermediate point of serial data), the serial data output port Ps is set to“ 000101 ”, and the output bit counter B is“ 15 ”(first stop). When the bit Sto1), the serial data output port Ps is set to “1”, and when the output bit counter B is “16” (second start bit Sta2), the serial data output port Ps is set to “0”. The output bit counter B is “24, 25, 26, 27, 28, 29” (second data indicating the end point of serial data). Serial data output port Ps is set to “110010”, and when output bit counter B is “30” (second stop bit Sto2), serial data output port Ps is set to “1”. Set. All of these data are predetermined fixed data.

  Next, the processes from step S1 to step S52 are repeated and the second serial data output is completed. In this way, the same serial data can be output from the temperature control unit 1 twice in succession.

  On the other hand, in the temperature display unit 3, the second microcomputer 31 detects the serial data output from the temperature control unit 1, a minus bit representing a positive or negative sign in the detected serial data, and 10 Based on the first display data string representing the first digit and the second display data representing the first digit, the minus display LED 321, the seven-segment LEDs 322 and 323 of the display circuit 32 are dynamically driven. The lighting is controlled by.

  Here, the second microcomputer 31 has a function in which the CPU 315 detects serial data input to the CPU 315 from the signal input circuit 33 via the I / O circuit 314 at every predetermined time measured by the timer 313. The serial data detected by the CPU 315 is stored in the RAM 312.

  Further, in the second microcomputer 31, the ROM 311 stores a first fixed data string that represents an intermediate point of serial data and a second fixed data string that represents the end point of serial data. The serial data stored in the RAM 312 is compared with the first fixed data string and the second fixed data string stored in the ROM 311, and the first fixed data string and the second fixed data string on the serial data are compared. It has a function of detecting and detecting the first display data string and the second display data string on the serial data from the position.

  Furthermore, in the second microcomputer 31, if the CPU 315 cannot detect the first fixed data string and the second fixed data string from the serial data stored in the RAM 312 a predetermined number of times, the timer 313 It has a function of changing a measurement time, changing a predetermined time for detecting serial data input to the CPU 315, and changing an interval at which the CPU 315 detects serial data.

  In addition, in the second microcomputer 31, when the CPU 315 detects serial data, each bit of the serial data is detected a plurality of times, the number of detections is counted for each detected input level, and stored in the RAM 312. In addition, the CPU 315 has a function of comparing the number of detections of each input level and storing a level with a large number of detections in the RAM 312 as a detection level of the bit.

  Further, in the second microcomputer 31, the display data string table shown in FIG. 3 is stored in the ROM 311, and the first display data string and the second display data string detected from the serial data are stored in the ROM 311. Each of the display data string tables is stored in the RAM 312 only when the detected data string matches any one display data string in the table, and a display signal corresponding to these data is stored. It has a function of outputting to the display circuit 32.

  Furthermore, in the second microcomputer 31, the minus bit data detected by the CPU 315, the first display data string, and the second display data string are stored in the RAM 312 for two consecutive serial data inputted. The CPU 315 has a function of comparing the stored data for the two periods and outputting a display signal corresponding to the data to the display circuit 32 only when they match each other.

  In the second microcomputer 31, when the first display data string and the second display data string detected by the CPU 315 do not match the display data string table stored in the ROM 311 a predetermined number of times. The timer 313 has a function of changing a measurement time, changing a predetermined time for detecting serial data input to the CPU 315, and changing an interval at which the CPU 315 detects serial data.

  In the temperature control device of the showcase having such a function, the second microcomputer 31 of the temperature display unit 3 is output from the first microcomputer 11 of the temperature control unit 1 by 1 bit, for example, every 3 mSec. Serial data to be input to the CPU 315 from the I / O circuit 314, and the CPU 315 detects the input serial data every time the timer 313 measures, for example, every 1 mSec.

  The CPU 315 counts the number of times Hi when the input level of the detected serial data is Hi, and counts the number of times Lo when the detected input level of the serial data is Lo. After the third count is reached, the counted number of Hi and the number of Lo are compared, and the larger one is stored in the RAM 312 as the input level of the bit. In this way, even if external noise or the like enters the serial data input to the second microcomputer 31 through the long lead wire 5 and the input level changes, the CPU 315 accurately sets the input level of the serial data. Can be detected.

  By repeating this operation, the CPU 315 detects all the bits of one cycle of the serial data, stores all the detected bits in the RAM 312, and represents an intermediate point between the stored serial data and the serial data stored in the ROM 311. The first fixed data string and the second fixed data string representing the end point of the serial data are compared, and the first fixed data string and the second fixed data string are detected from the serial data.

  At this time, if the first fixed data string and the second fixed data string cannot be detected a predetermined number of times, the CPU 315 changes 1 mSec, which is the measurement time of the timer 313, and changes the interval at which the CPU 315 detects serial data. . In other words, when the first fixed data string and the second fixed data string cannot be detected from the serial data, the first micro data line is caused by a variation in manufacturing part characteristics or a change in part characteristics due to a temperature change. Since the operation clocks of the computer 11 and the second microcomputer 31 do not match, the time measured by the timer 116 in the first microcomputer 11 and the time measured by the timer 313 in the second microcomputer 31 are different. The measurement time of the timer 313 in the second microcomputer 31 is synchronized with the measurement time of the timer 116 in the first microcomputer 11 by changing the measurement time of the timer 313 in the second microcomputer 31. Can be adjusted as follows. This operation is repeated until the second microcomputer 31 detects the first fixed data string and the second fixed data string from the serial data, and finally the measurement time of the timer 313 in the second microcomputer 31 is reached. However, since the first fixed data string and the second fixed data string can be detected from the serial data in synchronization with the measurement time of the timer 116 in the first microcomputer 11, the timing for detecting the serial data The second macro computer 31 can detect the serial data output from the first microcomputer 11 even if there is no clock signal for obtaining the signal, and as a result, a signal line that enables serial data transmission / reception. Requires only one lead wire for serial data.

  Next, the CPU 315 represents the tenth digit on the serial data from the positions of the first fixed data string and the second fixed data string on the detected serial data according to the arrangement of the serial data shown in FIG. The first display data string and the second display data string representing the number of the first place are detected. Next, in the second microcomputer 31, the CPU 315 compares the detected first display data string and second display data string with the display data string table shown in FIG. 3 stored in the ROM 311. The first display data string and the second display data detected only when the detected first display data string and the second display data string coincide with any one display data string in the display data string table of the ROM 311. The columns are stored in the RAM 312, and display signals corresponding to these data are output to the display circuit 32. By doing so, external noise or the like enters the serial data input to the second microcomputer 31 through the long lead wire 5, and the input level of the serial data changes, so that the first display data string and the first data Even when the display data string 2 is detected as illegal display data different from the predetermined display, the CPU 315 can cancel the illegal display data and prevent an erroneous display error.

  Further, in the second microcomputer 31, the CPU 315 outputs negative bit data of serial data for two consecutive periods output from the first microcomputer 11, the first display data string, and the second display data. Each column is stored in the RAM 314, and the CPU 315 compares the stored data for the two periods, and outputs a display signal corresponding to the data to the display circuit 32 only when they match. In this way, external noise or the like enters the serial data input to the second microcomputer 31 through the long lead wire 5, the input level of the serial data changes, and negative bit data or the first display is displayed. Even when the data string and the second display data string are illegal display data different from the data output from the first microcomputer 11, the CPU 315 compares the data for two periods to thereby detect the illegal data. The display data can be canceled and unfair erroneous display can be prevented.

  In the second microcomputer 31, the first display data string and the second display data string detected by the CPU 315 are detected when compared with the display data string in the display data string table stored in the ROM 311. When the first display data string and the second display data string do not coincide with any of the display data strings in the display data string table a predetermined number of times, the CPU 315 changes the measurement time of the timer 313, The predetermined time for detecting serial data input to the CPU 315 is changed, and the interval at which the CPU 315 detects serial data is changed. That is, when the first display data string and the second display data string cannot be detected from the serial data, the first micro data may be caused by a variation in manufacturing part characteristics or a change in part characteristics due to a temperature change. Since the operation clocks of the computer 11 and the second microcomputer 31 do not match, the time measured by the timer 116 in the first microcomputer 11 and the time measured by the timer 313 in the second microcomputer 31 are different. The measurement time of the timer 313 in the second microcomputer 31 is synchronized with the measurement time of the timer 116 in the first microcomputer 11 by changing the measurement time of the timer 313 in the second microcomputer 31. Can be adjusted as follows. This operation is repeated in the second microcomputer 31 until the detected first display data string and second display data string match any one of the display data strings in the display data string table in the ROM 311. Finally, the measurement time of the timer 313 in the second microcomputer 31 is synchronized with the measurement time of the timer 116 in the first microcomputer 11, and the first display data string and the second display data string are selected from the serial data. Therefore, the second microcomputer 31 can output the serial data output from the first microcomputer 11 without a clock signal for obtaining the timing for detecting the serial data. Can be detected, and as a result, serial data can be sent and received Route As may only lead one for serial data.

  The serial data detection process in the second microcomputer 31 of the temperature display unit 3 will be described with reference to FIG. In the second microcomputer 31, the RAM 312 includes a Hi counter H that counts when the serial data input level is Hi, a Lo counter L that counts when the serial data input level is Lo, and serial data detection. A detection number counter T for counting the number of times, a data memory DATA for storing the detected serial data for 31 bits one bit at a time, a negative bit detected first time, a first display data string, and a second display data string are stored. The memory X, the memory Y storing the minus bit detected this time, the first display data string and the second display data string, and the first fixed data string or the second fixed data string cannot be detected, or the first 1 display data string or 2nd display data string does not match the display data string table A detection error counter E that counts the number of occurrences and a memory S that stores display data are secured, and the ROM 311 stores the display data string table shown in FIG. The circuit 314 is provided with an input port Pr for inputting serial data.

  Here, in the second microcomputer 31, when the program stored in the ROM 311 is executed, the initialization program causes the Hi counter H, the Lo counter L, the detection number counter T, the data memory DATA, the memory X, The memory Y and the error counter E are cleared to “0”. Next, the main program is executed, and in the second microcomputer 31, the CPU 315 outputs the display data stored in the memory S secured in the RAM 312 to the display circuit 32 via the I / O circuit 314. 32 is controlled by a dynamic drive system and the internal temperature is displayed. Here, the detection processing of the serial data in the second microcomputer 31 shown in FIG. 5 is a timer interrupt program stored in the ROM 311. When the CPU 315 starts measuring the time of the timer 313 in the initialization program, Based on the measurement time of the timer 313, a timer interrupt is generated every 1 mSec, and the timer interrupt program shown in FIG. 5 is executed.

  In the second microcomputer 31, when a timer interrupt occurs every 1 mSec based on the measurement time of the timer 313, the timer interrupt program in FIG. 5 starts. First, the CPU 315 starts from the input port Pr of the I / O circuit 314. The input serial data is detected, and it is determined whether or not the input level is “1” (Hi) (S101). When the input port Pr is “1”, the Hi counter H of the RAM 312 is incremented by “1” (S102). When the input port Pr is not “1”, since the input level is “0” (Lo), the Lo counter L of the RAM 312 is incremented by “1” (S103). Next, it is determined from the value of the detection number counter T in the RAM 312 whether or not the detection of serial data has been completed a predetermined number of times, for example, three times (S104). When the detection number counter T is “2”, the predetermined number of detections are completed, the detection number counter T is reset to “0” (S105), and the contents of the Hi counter H and Lo counter L are compared in size. (S106).

  Here, when the content of the Hi counter H is large, the content of the data memory DATA of the RAM 312 storing the detected 31-bit serial data is first shifted to the left by 1 bit (S107), and 0 of the same data memory DATA is stored. “1” is set to the bit (S108). When the content of the Lo counter L is large, the content of the data memory DATA of the RAM 312 storing 31-bit serial data detected is first shifted to the left by 1 bit (S109), and the 0th bit of the same data memory DATA is stored. “0” is set (S110). Next, the contents of the Hi counter H and Lo counter L are reset to “0” (S111).

  Next, the CPU 315 shifts the serial data 31 bits stored in the data memory DATA one bit at a time in units of 6 bits while shifting the first fixed data string “000101” representing the intermediate point of the serial data stored in the ROM 311. Is compared with the first serial data string “000101” in the stored 31 bits of serial data (S112). Here, when there is a first fixed data string “000101” in the data memory DATA, the CPU 315 further selects 31 bits of serial data stored in the data memory DATA according to the serial data arrangement shown in FIG. 6 bits of continuous data 10 bits behind the detected first fixed data string and the second fixed data string “110010” representing the end point of the serial data stored in the ROM 311 are compared and stored. It is determined whether there is a second fixed data string “110010” at a predetermined position of the 31-bit serial data (S113).

  Further, when there is a second fixed data string “110010” in the data memory DATA, the CPU 315 detects the serial data 31 bits stored in the data memory DATA according to the serial data arrangement shown in FIG. FIG. 7 is a diagram in which 7-bit data immediately before the first fixed data string is detected as a first display data string representing a digit of the tenth digit, and the detected first display data string and the ROM 311 store the detected first display data string. 3 is compared with the display data sequence table shown in FIG. 3 to determine whether or not the detected first display data sequence matches any one display data sequence in the display data sequence table, and stored in the data memory DATA. Of the 31 bits of serial data, the detected data immediately before the second fixed data string is detected according to the serial data arrangement shown in FIG. The subsequent 7-bit data is detected as a second display data string representing the number of the 1's digit, and the detected second display data string and the display data string table shown in FIG. The comparison is made to determine whether the detected second display data string matches any one display data string in the display data string table (S114).

  If it is determined in step S114 that the first display data string and the second display data string detected from the data memory DATA coincide with any one of the display data string tables in the ROM 311, the COU 315 receives the serial number shown in FIG. According to the arrangement of the data, one bit immediately before the detected first display data string is detected as minus bit data, the detected minus bit data, the first display data string and the second display data string are Is stored in the memory Y secured in the RAM 312 as the data detected this time (S115). Next, the CPU 315 detects the minus bit data of the memory Y detected this time, the first display data string and the second display data string, the minus bit data previously detected and stored in the memory X of the RAM 312, The first display data string and the second display data string are respectively compared to determine whether or not they match (S116). If they match, the minus bit data in the memory Y, the first display data string, Display data corresponding to the second display data string is set in the display data storage memory S provided in the RAM 312 (S117). Here, the CPU 315 reads the display data stored in the memory S of the RAM 312 in the main program, outputs the read display data to the display circuit 32 via the I / O circuit 314, and the minus display LED 321 of the display circuit 32. Then, the 7-segment LEDs 322 and 323 are controlled by the dynamic drive method, and the internal temperature is displayed on the display circuit 32. In step S 116, when the previously stored data in the memory X does not match the current stored data in the memory Y, the CPU 315 does not set the detected display data in the display data storage memory S of the RAM 312 because the data is not accurate.

  Next, the CPU 315 stores the minus bit data of the memory Y of the RAM 312 detected this time, the first display data string, and the second display data string in the memory X of the RAM 312 as previously detected data (S1171). After that, since the detection of the serial data is normally performed, the first fixed data string or the second fixed data string cannot be detected, or the first display data string or the second display data string is the display data string. The detection error counter E that counts the number of times when the table does not match is cleared to “0” (S118).

  If the detection number counter T that counts the number of detections of serial data in the RAM 312 does not reach a predetermined number, for example, 3 times (T = 2) in the determination in step S104, the serial data detection process is still executed 3 times. Since it is not implemented, the detection number counter T is incremented by “1” (S119), and the processing from step S105 to step S118 is not executed. Furthermore, the first fixed data string cannot be detected in step S112, the second fixed data string cannot be detected in step S113, or the first display data string or the second data in step S114 is not detected. When the display data string does not match any of the display data string tables, it is determined that the serial data cannot be accurately detected, and the detection error counter E of the RAM 312 is incremented by “1” (S120).

  Next, the CPU 315 determines whether or not the detection error counter E in the RAM 312 exceeds the maximum number of errors, for example, 155 (S121). If the detection error counter E exceeds 155, the detection error counter E is first reset to “0”. Next, for example, “1” is subtracted from the timer data TD for time measurement of 1 mSec set in the timer 313 (S123). Thereafter, the CPU 315 determines whether or not the timer data TD is smaller than a predetermined minimum setting value TDmin of the timer data TD stored in the ROM 311 (S124). If the timer data TD is smaller, the timer data TD is stored in the ROM 311. The processing of the timer interrupt program is terminated with the predetermined maximum setting value TDmax of the timer data TD. When the detection error counter E is smaller than 155 in step S121 and when the timer data TD is greater than or equal to the minimum set value TDmin in step S124, the subsequent processing is not performed and the processing of the timer interrupt program is terminated. .

  Here, in the determination in step S121, the maximum value 155 of the detection error counter E is 5 cycles of 31-bit serial data. When the CPU 315 cannot detect serial data accurately for 5 consecutive cycles, It is determined that the time measured by the timer 313 of the microcomputer 31 is not synchronized with the time measured by the timer 116 of the first microcomputer 11, and “1” is obtained from the timer data TD for the timer 313 to measure 1 mSec. By subtracting, the generation time of the timer interrupt is changed, and the CPU 315 changes the interval for detecting the serial data input from the input port Pr in step S101, and further repeats this, so that finally the second microcomputer The time measured by 31 timers 313 is the first B in synchronization with the time when the timer 116 of the computer 11 is measured, it is possible to accurately detect the serial data. In addition, the minimum value TDmin and the maximum value TDmax of the timer data TD in step S124 and step S125 are set to appropriate values in consideration of variations in manufacturing component characteristics, changes in characteristics due to temperature conditions, and the like. Thus, the change range of the timer data TD can be reduced, and as a result, the synchronization can be quickly established. Therefore, the subtraction is repeated more than necessary in step S123, and the measurement time of the timer 313 of the second microcomputer 31 is determined. However, a time longer than necessary does not elapse before the time measured by the timer 116 of the first microcomputer 11 is synchronized.

  In this way, by incorporating the predetermined first fixed data string and second fixed data string into the serial data transmitted from the first microcomputer 11 of the temperature control unit 1, The second microcomputer 31 first detects the first fixed data string and the second fixed data string in the serial data, and then, from the serial data array, minus bit data as display data, and the first Since the display data string and the second display data string can be detected, a clock signal different from the serial data is not required, and communication is possible with only one signal line for transmitting and receiving serial data.

  When the second microcomputer 31 cannot detect the first fixed data string and the second fixed data string from the serial data, the measurement time of the timer 313 for determining the interval at which the CPU 315 detects the serial data. And the timer 116 of the first microcomputer 11 and the timer 313 of the second microcomputer 31 are synchronized with each other. As a result, the second microcomputer 31 has the first fixed data string in the serial data. And the second fixed data string can be detected, and the negative bit data as the display data, the first display data string, and the second display data string can be detected from the serial data array. Due to changes in the characteristics of the components and changes in the characteristics of the components due to temperature changes, the first microcomputer 1 of timer 116, be different from the measurement time of the timer 313 of the second microcomputer 31, it is possible to synchronize this result, it is possible to transmit and receive serial data without clock signal.

  Even if the temperature control unit 1 and the temperature display unit 3 are connected by the long lead wire 5 and serial data is transmitted and received without a clock signal, the CPU 315 of the second microcomputer 31 converts the input serial data into 1 Since a bit is detected three times and an input level with a large number of detections is stored in the RAM 312 as data of the bit, even if external noise or the like enters the input serial data and the input level changes, this is detected. By eliminating this, it is possible to prevent erroneous detection of serial data, and consequently to prevent erroneous display on the display circuit 32. Further, the second microcomputer 31 cannot detect the first fixed data string and the second fixed data string from the detected serial data, or the first display data string in the detected serial data or If the second display data string does not match any of the display data string tables stored in the ROM 311, or the previously detected minus bit data, the first display data string, the second display data string, and the current detection If the minus bit data, the first display data string, and the second display data string do not match, the CPU 315 does not update the display data, so the serial data output by the first microcomputer 11 is Even if external noise or the like enters and the input level changes, this is eliminated and erroneous display on the display circuit 32 is prevented. It can be.

The block diagram explaining the structure of the temperature control apparatus of the showcase concerning this invention. The time chart figure explaining the example of arrangement of serial data used by the present invention. The figure explaining the example of the display data sequence table used by this invention. The flowchart figure explaining the production | generation and output process of the serial data in the temperature control part of this invention. The flowchart figure explaining the detection process of the serial data in the temperature display part of this invention. The block diagram explaining the structure of the temperature display apparatus of the conventional showcase.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Temperature control part 11 ... Microcomputer 111 ... CPU
112 ... ROM
113 ... RAM
114 ... I / O circuit 115 ... A / D converter 116 ... Timer 12 ... resistance circuit 13 ... switch circuit 14 ... display circuit 15 ... relay circuit 16 ... signal output circuit 3 ... temperature display unit 31 ... microcomputer 311 ... ROM
312 ... RAM
313 ... Timer 314 ... I / O circuit 315 ... CPU
32 ... Display circuit 321 ... Negative display LED
322 ... 10-segment display 7-segment LED
323 ... 1-segment display 7-segment LED
33 ... Signal input circuit 5 ... Lead wire 7 ... Thermistor 9 ... Compressor

Claims (12)

A temperature control unit for controlling the temperature inside the showcase; and a temperature display unit for displaying the temperature inside the showcase; and the temperature control unit and the temperature display unit are connected by a signal line. In the case temperature control device,
The temperature control unit has a first microcomputer, temperature detection means for detecting the temperature in the showcase, compressor control means, and signal output means connected to the signal line,
The first microcomputer compares the internal temperature detected by the temperature detection means with a set temperature to control the compressor control means,
Converting the temperature to be displayed on the temperature display unit into a display data string, generating serial data having the display data string and a predetermined fixed data string, and outputting the serial data to the signal output means; While outputting the serial data to the temperature display unit via the signal line,
The temperature display unit includes a second microcomputer, a signal input unit connected to the signal line, and a temperature display unit.
The second microcomputer receives the serial data from the signal input means, detects the fixed data string and the display data string from the serial data, and outputs a signal corresponding to the display data string to the temperature display means. A temperature control device for a showcase, characterized in that the temperature is output to the display.   The serial data includes a minus bit indicating a positive or negative sign of a temperature to be displayed, a first display data string indicating a tenth digit of the temperature to be displayed, and a second display indicating a first digit. 2. The temperature control device for a showcase according to claim 1, further comprising a data string and a first fixed data string and a second fixed data string which are determined in advance.   3. The first fixed data string and the second fixed data string are arranged differently from the first display data string and the second display data string, respectively. The temperature control device of the showcase as described.   The first fixed data string and the second fixed data string have a data length of 6 bits, the first fixed data string is an array of “000101” or “110010”, and the second fixed data string The temperature control device for a showcase according to any one of claims 1 to 3, wherein is an arrangement of "110010" or "000101".   5. The temperature control device for a showcase according to claim 1, wherein the first display data string and the second display data string have a data length of 7 bits.   The serial data arrangement includes a first start bit, the minus bit, the first display data string, the first fixed data string, the first stop bit, the second start bit, and the second data bit. 6. The temperature control device for a showcase according to claim 1, comprising a display data string, the second fixed data string, and a second stop bit.   The showcase according to any one of claims 1 to 6, wherein data displayed on the temperature display unit is a number or a symbol based on the serial data output from the temperature control unit. Temperature control device.   2. The second microcomputer detects the serial data at predetermined time intervals, and changes the predetermined time when the fixed data string cannot be detected a predetermined number of times. The temperature control device for a showcase according to any one of claims 7 to 9.   When detecting the serial data, the second microcomputer detects each bit of the serial data a plurality of times, counts the number of detections for each detected level, and sets the level with the highest number of detections to The temperature control device for a showcase according to any one of claims 1 to 8, wherein the temperature control device is bit data.   The second microcomputer has a predetermined data string table, the data string table is compared with the detected display data string, and the display data string is one of the data string tables. 10. The showcase according to claim 1, wherein the temperature is displayed by outputting a signal corresponding to the display data string to the temperature display means only when the data string matches. Temperature control device.   The first microcomputer continuously outputs the serial data having the same display data string a plurality of times, and the second microcomputer outputs the display data string in the inputted serial data a plurality of times. 11. The showcase according to claim 1, wherein the temperature is displayed by outputting a signal corresponding to the display data string to the temperature display means only when they all match. Temperature control device. The second microcomputer has a predetermined data string table, the data string table is compared with the detected display data string, and the display data string is one of the data string tables. 12. The temperature control device for a showcase according to claim 1, wherein the predetermined time for detecting the serial data is changed when the data string does not coincide with the data string a predetermined number of times. .

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