JPS63132113A - Transducer - Google Patents

Abstract

PURPOSE:To equalize the mean value of a controlled variable to a set value by setting an upper- and a lower-limit on point and an upper- and a lower-limit off point above and below the upper- and lower-limit values and hysteresis value of an input signal, and turning on and off relays for upper- and lower-limit value output by the digitized input signal. CONSTITUTION:The input signal is supplied to a microcomputer 5 through an A/D converter 4 from a sensor input circuit 3. The upper- and lower-limit values and hysteresis of the input signal are inputted with push-button switches PB1-PB5, and a setting means 5S sets the upper-limit value on point HON and upper-limit off point HOFF, and lower-limit value OFF point LOFF and lower- limit value ON point LON above and below the upper- and lower-limit values. Those are stored in a storage means 5R. A comparing means 5C excites the relay XH for upper-limit value output and relay XL for lower-limit value output when the current value increases above the point HON and deceases below the point LON, and turns off the relays XH and XL when the value decreases below the point HOFF and increases above the point LOFF, thereby equalizing the mean value of the controlled variable to the set value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to transducers for converting physical quantities such as current, voltage, temperature, pressure, etc. into linearized outputs over a predetermined range.

[Prior art and its problems]

(Prior art) Conventional transducers and temperature transducers convert voltage from a temperature sensor such as a thermocouple into a DC voltage within a predetermined range, and voltage transducers are, for example, voltage transformers (P
The voltage obtained from T) is converted into a DC voltage within a predetermined range. Such various conventional transducers have only the function of converting an input physical quantity into a DC voltage within a predetermined range corresponding to the input physical quantity. Then, it is necessary to use a meter relay to display the input value, set the lower limit value and upper limit value of the input value, and obtain an output when the input value exceeds the range.

(Problems to be Solved by the Invention) However, since the transducer and the meter relay are independent devices and must be wired separately, there is a problem in that the wiring becomes complicated and the installation space becomes large. Another problem is that the output voltage of the transducer and the upper and lower limits at which the meter relay operates do not necessarily match, making it difficult to use.

In addition, when controlling a controlled object using the contact relay output of a conventional meter relay, for example, when controlling the temperature of a heating furnace on and off using the output of a lower limit relay, the meter The relay will turn on and off repeatedly. Therefore, there are problems in that the life of the contact relay is shortened and noise may be continuously generated from the relay.

Therefore, in order to solve this problem, it may be possible to provide hysteresis to the relay output of the meter relay.

However, when hysteresis is provided, there is a drawback that the set value and the control temperature are different.

[Technical issues]

The present invention has been made in view of the problems of conventional transducers, and provides a function for setting a predetermined range of input values in a transducer that converts an input signal into a DC voltage within a predetermined range, and a function for setting a predetermined range of input values and the range thereof. In addition to adding and integrating the function of a meter relay that obtains an output when the limit value is exceeded, the relay output is used to control the controlled object by setting the dark value of the relay output above and below the set values of the upper and lower limits, respectively. In some cases, the technical challenge is to make the controlled amount equal to the set value.

[Structure and effects of the invention]

(Means for Solving the Problems) The present invention is a transducer that converts an input signal into a signal with a level corresponding to the input signal, and as shown in FIGS. 1 and 5, converts an analog input signal into a digital signal. an A/D converter for converting the input signal into an input signal, an input means for inputting the upper and lower limits of the input signal and their hysteresis, and storing the current value and the upper and lower limit values and hysteresis values set by the upper and lower limit value setting means. A storage means sets an upper limit on point and an upper limit off point with a hysteresis width above and below the upper limit value held in the storage means, and sets a lower limit value with a hysteresis width above and below the lower limit value. Off point 1 lower limit setting means for setting the on point, on points and off points set above and below the upper and lower limit values held in the storage means, respectively, and input A/D converted by the A/D converter. a comparison means for comparing the signal;
It has output relays for upper and lower limit values that correspond to upper and lower limit values, respectively.
When the current value rises beyond the upper limit ON point and falls beyond the lower limit ON point as a result of comparison by the comparison means, the output relays for the upper and lower limit values are energized, and the current value exceeds the upper limit OFF point. Output means for deenergizing the output relays for the upper and lower limit values when the lower limit value falls or rises beyond the lower limit off point, respectively, and a human input signal converted from A/D by the A/D converter in proportion to the level thereof. The device is characterized in that it includes a D/A converter that converts the signal into a digital signal.

(Operation) According to the present invention having such features, the upper and lower limit values and the hysteresis value set in advance are stored in the storage means, and the input signal is stored in the upper and lower limit values and the hysteresis value set by the setting means. Upper and lower limit ON points and upper and lower limit OFF points are set above and below, respectively. When the input signal rises beyond the upper limit ON point or falls beyond the lower limit ON point, the respective output relays are energized. Further, the A/D converted value of the input signal is again D/A converted to a predetermined level and outputted to the outside.

When the value falls beyond the upper limit off point set above or below the upper limit value or rises beyond the lower limit off point, the respective relays are deenergized.

(Effects of the Invention) Therefore, according to the present invention, a transducer can obtain a linearized output in a predetermined range corresponding to an input signal, and has a meter relay function that provides an output when the input signal exceeds the upper and lower limits. It can be done. Furthermore, compared to the case where a conventional transducer and meter relay are used, the number of wiring in the input section is reduced, and the configuration can be simplified. Furthermore, when operating the controlled object using the relay output of a transducer based on the sensor output from the controlled object, the relay is activated when the controlled amount approaches the set value.

Since the deenergization is repeated at predetermined intervals, the relay does not become disconnected in a short period of time. Therefore, the noise generated from the relay can be reduced, and the life of the relay can also be extended. Furthermore, when controlling a controlled object using output relays for upper and lower limit values, the on point and off point are provided above and below the set value, respectively, so the average value of the controlled variable is approximately set regardless of the hysteresis value. Can be matched with a value.

[Explanation of Examples]

(Configuration of Embodiment) FIG. 1 is a block diagram showing the electrical configuration of an embodiment of a transducer according to the present invention, and FIG. 2 is a diagram showing the front panel surface thereof. This embodiment uses a transducer that converts the temperature of a temperature sensor such as a thermocouple in a predetermined range into a DC output of, for example, 0 to 5 cm. In these figures,
A sensor input circuit 3 is connected between input terminals 2a and 2b of the transducer 1. The sensor input circuit 3 amplifies the output from the temperature sensor to a predetermined level and provides the output to the A/D converter 4. The A/D converter 4 converts the analog signal applied at a predetermined timing into a digital signal and provides the output to the microcomputer 5. The microcomputer 5 is a control element having therein a microprocessor, an input/output interface, and a storage means 5R containing a control program and a group of registers shown.

The storage means 5R in the microcomputer 5 contains a PV flag, an H flag, an L flag indicating the display state, and a HYS flag set when hysteresis is set.

There are also flag registers for the XH flag and XL flag, which are set when the relay is driven when the current value exceeds the upper and lower limits, and further includes a pv value register that stores the current value, and a pv value register that stores the upper limit set value. The H setting value register, which stores the lower limit setting value, the HYS register which stores the setting value register and the hysteresis width, and the upper limit on point (hereinafter referred to as Hon level) and upper limit value off point (hereinafter referred to as Hon level) provided above and below the upper limit value, respectively. Hoff level), a lower limit off point (hereinafter referred to as Loff level), and a lower limit on point (hereinafter referred to as Lon level) provided above and below the lower limit value, respectively. The microcomputer 5 also includes a slide switch SLI for switching between set mode and run mode, and push button switches PBI to PB4 for setting numerical values to sequentially switch the display of each digit on the display.
A push-button switch PB5 for switching display contents is connected. PB1 to PB5 constitute input means for inputting upper and lower limit values and hysteresis of the input signal. Matama・
The microcomputer 5 is provided with an output from a model selection switch 6. The model selection switch 6 provides data for setting this transducer to a predetermined input/output specification, and it is necessary to use the sensor input circuit 3 corresponding to the input/output specification.

The microcomputer 5 provides the current value to the display 7 and the launch circuit 8 at predetermined time intervals based on these externally applied inputs. The latch circuit 8 holds the output of the microcomputer 5 for a predetermined period of time, and supplies the output to the D/A converter 9. The D/A converter 9 converts the digital signal into an output corresponding to the signal, for example, a DC output of 0 to 5 cm, and supplies the converted signal to the outside through output terminals 10a and 10b. The microcomputer 5 has a Hon level set above and below the set upper limit and lower limit.

Setting means 53 for setting Hoff level, Loff level, and Lon. Comparing means 5C is configured to compare these levels with the A/D conversion value, and when these upper and lower limits are exceeded, an output is given to the output buffer 11. The output buffer 11 drives a relay XH for outputting an upper limit value or a relay XL for outputting a lower limit value in response to these inputs.

Relays XH and XL have normally open contacts connected between terminals 12a, 12b and 13a, 13b, respectively, and output from these terminals to the outside.

The output buffer 11 and relays XH and XL constitute an output means that outputs an output when the input current value exceeds the upper and lower limits. Furthermore, when relays XH and XL are driven, the output buffer 11 outputs light emitting diodes (hereinafter referred to as LEDs) at the top of each panel.
14 and 15 are respectively driven. Further, a PV display LED 16, an H display LED 17, which indicates the current output of the display 7 from the microcomputer 5. LE for L display
D18 is connected. - Commercial AC power is applied to the power supply section 20 from terminals 19a and 19b, supplying DC power to each section.

(Example of Use of Transducer) Next, FIG. 3 is a block diagram showing an example of using the transducer according to this embodiment as a temperature sensor. In this figure, if the controlled object 21 is, for example, a heating furnace, a temperature sensor 22 such as a thermocouple is attached to the controlled object 21, and its output is given to the transducer 1 according to this embodiment. And the relay output of this transducer 1,
For example, the output of a relay XL for outputting a lower limit value is given to the output section 23. The output unit 23 constitutes, for example, a heater that heats the controlled object 21, and controls the controlled object 21 to be turned on and off by the contact output of the relay XL.

(Upper/Lower Limit Value Setting Operation) Next, the operation of the transducer of this embodiment will be described with reference to a flowchart. FIG. 4 is a flowchart showing the operation when setting the upper limit value, lower limit value and hysteresis for providing a relay output from this transducer, and FIG. 5 is a flowchart in the operation mode.

When the operation starts, first, in step 31 of FIG. 4, it is checked whether or not the set mode is set. Switch SLI
If it is set to the set mode, the process advances to step 32 and it is checked whether the push button switch PB5 is pressed. When this push button switch is pressed, the flag register is updated so that the PV flag, H flag, L flag, and HYS flag are set in sequence. Steps 33), 34, 35, and 36 proceed to the H flag,
Check whether the L flag or HYS flag is set.

If the H flag is set, the process advances from step 34 to step 37, where the LED 18 is turned off, the LED 17 is turned on, rHJ is displayed on the panel surface, and the upper limit value setting routine 38 is performed.
to go into. In this routine 38, numerical values for each digit of the display 7 are set using push button switches PBI to PB4 for numerical value setting, and the upper limit value is stored in the H set value register.

When this setting is completed, the process returns to step 31, and it is determined whether or not the set mode is set, and the same process is repeated. When the L flag is set by updating the flag register in step 33, the process proceeds from step 35 to step 39, where the LED 17 is turned off and the LED 18 is turned on to display rLJ on the panel surface. And lower limit value setting routine 40
Proceed to step 38 and press the push button switch PB.
Set the numerical value of each digit of the display 7 using I to PB4,
Store the lower limit value in the set value register in memory. Then, the process returns to step 31 and the same process is repeated. If the HYS flag is set by updating the flag register in step 33, step 36 to step 4
Proceed to step 1 and turn on the two LEDs 17 and 18. Then, proceed to routine 42, and similarly to the upper and lower limit values, set the numerical values of each digit of the display 7 using the push button switches PBI to PB4, and set the hysteresis value to the HYS for hysteresis.
Store it in the register and end the setting process.

(Operation in run mode) After setting the upper limit value and lower limit value, press the selector switch SL.
1 to run mode. The microcomputer 5 of the transducer checks whether it is set mode or run mode in step 31 and step 50. If it is not run mode, it proceeds to step 31, and if it is run mode, it proceeds to step 51 and presses the next push button switch. The inputs of PB1 to PB4 are invalidated. Then, in step 52, the data of the model selection switch 6 is read and the input/output specifications are determined in accordance with the data. For example, if the transducer of this embodiment uses a crab-shaped thermocouple (TC) as a temperature sensor and is a transducer that converts a temperature of 0 to 400 degrees Celsius into a DC voltage of 0 to 5 V, then step 53.54 Set to meet each specification. The sensor input circuit 3 amplifies the input voltage applied from the input terminals 2a and 2b. Its amplified output is A/D
Since it is added to the converter 4, the microcomputer 5 gives a sampling pulse to the A/D converter 4 at predetermined intervals, takes in the data converted to a digital value, and writes it into the Pv value register in the memory ( Step 55).

Then, the process proceeds to step 56, where it is checked whether the H flag is set, and if this flag is set, the upper limit value held in the already stored H setting value register is displayed on the display 7. , LED16.
18 is turned off and the LED 17 is turned on to display the H setting value (steps 57 and 58). If the L flag is set in step 59, the lower limit value held in the set value register in the memory is similarly displayed on the display 7 (step 60), and the process proceeds to step 61, where the LED 16. 17 is turned off and the LED 18 is turned on to display the L setting value. Furthermore, if the H flag and L flag are not set in steps 56 and 59, the process advances to step 62, where the current value in the PV value register taken in in step 55 is displayed on the display 7, and the latch is It is applied to the circuit 8 and temporarily held. Then step 63
At this point, the LEDs 17 and 18 are turned off and the LED 16 is turned on to display the current value, and the D/A converter 9 outputs a DC voltage from 0 to 5 cm corresponding to the input voltage to the terminal 10a.

10b to the outside (step 64).

Then, the process proceeds to step 65, where the upper limit value and lower limit value are set as on level and off level, respectively. The Hon level, which is the ON point of the H setting value, is a higher value of hysteresis than the H setting value (H setting value %HYS), and the H level is the OFF point of the H setting value.
The off level is set to a value A lower in hysteresis than the H setting value (H setting value - 'A HY S ) (step 65
), and the on-point Lon level of the set value is a value that is hysteresis % lower than the L set value (L set value - % HYS), and the L
The off point Loff level of the set value is set to a value with hysteresis A higher than the Ll constant value (L set value +!/5HYS) (step 66). After completing this process, proceed to step 67 to register the Pv value register. Check whether the current value in is equal to or higher than the Hon level. If the current value is higher than the Hon level, the process advances to step 68, turns off the XH flag and LED 14, and outputs the XH via the output buffer 11.
energize the relay. If the current value is less than the Hon level, the process advances to step 69 to check whether the Pv value is less than the Hoff level. If smaller than this value, step 7
0, the XH flag and LED 14 are turned off, and the XH relay is deenergized via the output buffer 11.

After completing the processing of steps 69 and 70, or if the current value is within the hysteresis near the H setting value, step 7
1 and checks whether the current value in the PV value register is below the Lon level. If it is below the Lon level, the XL flag and LED 15 are turned on and the XL relay is energized via the output buffer 11 (step 72).
. If the value exceeds the Lon level, the process proceeds to step 73 to check whether the value is lower than the Loff level. If it exceeds the Loff level, the process proceeds to step 74, where the XL flag and LED 15 are turned off, and the XL relay is deenergized via the output buffer 11. After completing the processing in steps 72 and 74, or if the current value is within the hysteresis range near the L setting value, the process proceeds to step 75 to check whether the pushbutton switch PB5 has been pressed. If the push button switch PB5 is not pressed, the process returns to step 50 and the same process is repeated, and if the push button switch PB5 is pressed, the P■ flag, H flag, and L flag in the flag register are updated so as to be set in sequence (step 76). Return to step 50.

Therefore, when the controlled object 21 is configured to be heated based on the output of the XL relay as shown in FIG. Figure (a).

As shown in (b), the XL relay is repeatedly energized and deenergized at regular intervals. Therefore, compared to the conventional case where on/off control is performed using the relay output of a meter relay, the number of relay operations can be reduced, noise generated from the relay is reduced, and the life of the output relay can be extended. The set values are shown in Figure 7 (a) and (b).
), rather than the level that energizes the XL relay.
Since this is midpoint reference control that is controlled based on the Lon level and Loff level that are set above and below the L setting value with a width of hysteresis, the control amount of the controlled object 21 as shown in FIG. 6(a) The average of a certain temperature is controlled to be almost the same as the L setpoint. Therefore, regardless of the width of the hysteresis, the controlled object can be controlled with a value that is almost the same as the set value.

Similarly, when cooling the controlled object based on the output of the XH relay, as shown in Figure 6 (C1, (d)), the H setting value is not directly set to the dark value level, but a hysteresis width is set above and below it. Hon level and Ho f f set with
Since the intermediate point reference control is performed based on the level, the cooler operates at the same value as the H setting value. Therefore, it is possible to perform control so that the set value and the average value of the control amount almost match.

In this embodiment, a thermocouple is used as a transducer as a temperature sensor, and the controlled object is controlled based on the relay output of the transducer. It is possible to apply the present invention to a transducer that accepts different inputs, such as a transducer that detects alternating voltage or current, or a transducer that converts the output of a potentiometer into a signal within a predetermined range.

In this embodiment, the same hysteresis value is set for the upper limit value and the lower limit value, but it goes without saying that different hysteresis values may be set for the upper and lower limit values.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a transducer according to the present invention, FIG. 2 is a front panel view thereof, and FIG. 3 is a block diagram showing an example of using this embodiment in a temperature control device.
Fig. 4 is a flowchart showing the operation in cent mode for setting the upper and lower limit values, Fig. 5 is a flowchart showing the operation in run mode, and Figs. 6(a) and (b) are the transducer of this embodiment. Figure 6 (cl, (dl) is a time chart showing the relationship between the XL relay output, set value, and control amount when the transducer of this example is used for temperature adjustment of a cooling system. X when used in equipment
A time chart showing the relationship between the output of the H relay, a set value, and a controlled amount, and FIG. 7 is a time chart showing an example of on-point control by the XL relay. 1...--Transducer 3--...
Sensor input circuit 4...--A/D converter
5-・-・・・Microcomputer 5C・−・
・-Comparison means 5 R----- Storage means
5S...-Setting means 6--Model selection switch 7--Display device 8--Latch circuit 9-=--D/A converter 10a,
l Ob---Output terminal 11...-
・Output sofa 14-18--Light emitting diode 21--Controlled object PB1-PB5
・−・−・・Push button switch (input means) XH,X
L...--Relay Fig. 2 Fig. 3

Claims (1)

[Claims] (1) A transducer that converts an input signal into a signal with a corresponding level, which includes an A/D converter that converts an analog input signal into a digital signal, and inputs the upper and lower limit values of the input signal and their hysteresis. input means; storage means for storing the current value, the upper and lower limit values set by the upper and lower limit value setting means, and a hysteresis value; a setting means for setting an upper limit value on point and an upper limit value off point, respectively, and setting a lower limit value off point and a lower limit value on point, respectively, with a hysteresis width above and below the lower limit value; From the on point and off point set above and below the upper and lower limit values, and the A/D converter,
It has a comparison means for comparing the D-converted input signal, and output relays for upper and lower limit values corresponding to the upper and lower limit values, respectively.
When the current value rises beyond the upper limit ON point and falls beyond the lower limit ON point as a result of comparison by the comparison means, the output relays for the upper and lower limit values are energized, and the current value exceeds the upper limit OFF point. an output means for deenergizing the output relays for the upper and lower limit values when the lower limit value falls and rises beyond the lower limit off point; A transducer comprising: a D/A converter that converts into a signal proportional to .