JPH05308365A - Communication line state display circuit - Google Patents

Abstract

PURPOSE:To reliably display a state wherein data are normally transmitted. CONSTITUTION:A communication system establishes a data link by a polling/ selecting system. An error detection part 24 detects whether or not there is an error in received data. A sequence decision part 25 decides the establishment of the data link. When the error detection part 24 detects no error and the sequence decision part 25 detects the establishment of the data link, a light emission diode LED3 illuminates through an output part 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a communication system in which a master station and a plurality of slave stations are branched and connected to each other to establish a data link by a polling / selecting method, and data is normally transmitted. The present invention relates to a communication line status display circuit that displays that the status is being changed.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a monitoring terminal 12 having switches S _{1 to} S ₃ and a lighting load L _{1 are provided.}
A remote control system 10 is provided in which a control terminal 13 to which L ₂ to L ₂ are connected is time-division-multiplexed to a main control device 11 via a signal line Ls. Address data is set individually for each of the monitoring terminal device 12 and the control terminal device 13, and the main control device 11 sets the address data for each monitoring terminal device 1.
2 and address data for individually selecting each control terminal device 13, control data for controlling each monitoring terminal device 12 and each control terminal device 13, and each monitoring terminal device 12
And a transmission signal having a signal return period which is a time slot for receiving the monitoring data returned from each control terminal device 13 is transmitted to the signal line Ls. When an interrupt signal is generated in the monitoring terminal device 12 based on the operation of the switches S _{1 to} S ₃ , the main control device 11 searches for the monitoring terminal device 12 that has generated the interrupt signal and performs the monitoring that generated the interrupt signal. The address data of the control terminal device 12 is acquired, and the control terminal device 13 in which the correspondence relationship with the monitoring terminal device 12 is set by the address data is accessed to control the lighting state of the lighting loads L _{1 to} L _2. It is like this.

The wireless receiving terminal 1 is connected to the signal line Ls.
4 is also connected, and when the wireless receiving terminal device 14 receives a wireless signal such as infrared rays from the wireless switch 15 provided outside, an interrupt signal is generated in the same manner as the monitoring terminal device 12, and the main control device 11 operates. At the time of search, the address data included in the wireless signal is returned to the main control device 11. Therefore, the switches S _{11 to} S provided on the wireless switch 15 are
₁₄ is accessed by the control terminal device 13 in which the correspondence relationship based on the address data is set, and the control terminal device 1 is accessed.
The lighting states of the lighting loads L _{1 to} L ₂ connected to the control unit 3 are controlled.

By the way, when the number of lighting loads L _{1 to} L ₂ is large, or when it is desired to provide one remote control system 10 for each floor in a building or the like, a plurality of main control devices 11 should be provided. is there. In this case, in order to collectively manage the plurality of remote control systems 10, the main controller 11
It is conceivable to provide a central control unit 1 higher than the above. That is, a higher-level communication system in which the central control device 1 is the main station and the main control device 11 is the slave station is constructed, and a plurality of main control devices 11 are branched and connected via the communication line Lt. Central controller 1 and main controller 11
A basic data transmission control procedure stipulated in JIS-X-5002 is adopted as a communication procedure to and from, and a data link is established by a polling / selecting method. Further, a higher-level central monitoring board 2 is connected to the central control device 1 via a communication line Lu. That is, a higher-level communication system in which the central monitoring board 2 is the main station and the central control device 1 is the slave station is constructed. The RS-232-C standard and the RS485 standard are adopted as the physical specifications of the communication lines Lt and Lu. Further, the setting device 3 is connected to the central control device 1 and the main control device 11 as required. The setting device 3 is connected to set address data and the like for a communication system higher than the remote control system 10.

By the way, in the central control unit 1, the central monitoring board 2, the main control unit 11, etc., there is a case where it is desired to confirm that the communication lines Lt and Lu connected to the central control unit 1 are normal and that the data is transmitted normally. is there. A display unit is provided to meet such a requirement. As shown in FIG. 4, the display unit 20 includes a processing unit 21 (comprising a microcomputer in which a dedicated program is set) provided in the central control unit 1, the central monitoring panel 2, the main control unit 11, etc. Corresponding to the reception data Rx and the transmission data Tx between the driver / receiver 22 that performs mutual change between the signal connected to Lt and Lu and transmitted through the communication lines Lt and Lu and the signal handled by the processing device 21, respectively. Connected. Here, the signal between the processing device 21 and the driver / receiver 22 is
As shown in FIG. 3, it is a signal of a fixed length having a start bit ST and a stop bit SP before and after, and normally 1
Each character (7 bits) has a start bit ST and a stop bit SP. Start bit ST
Has a logical value of 0 at all times, and the stop bit SP has a logical value of always 1, and logical values of 0 and 1 are at the L level,
If it corresponds to the H level, the presence or absence of the reception data Rx and the transmission data Tx can be detected depending on whether the signal is the H level or the L level. That is, the display unit 20 displays the reception data Rx and the transmission data Tx.
And buffers Bf ₁ and Bf ₂ , respectively, current limiting resistors R ₁ and R ₂ connected to the output terminals of the buffers Bf ₁ and Bf ₂ , and light emitting diodes LED ₁ and LED ₂ , respectively, and receive data Rx And the transmission data Tx becomes L level, the corresponding light emitting diodes LED ₁ , LE
D ₂ lights up. Therefore, when the stop bit ST passes, the light emitting diodes LED ₁ , L
ED ₂ lights up.

[0006]

The display unit 20 having the above-mentioned configuration is provided.
Can detect the presence or absence of the received data Rx and the transmitted data Tx, but since it only detects the change in the signal level, the transmission format and the like do not match and the communication is not actually established. Even the light emitting diode L
The ED ₁ and LED ₂ will light up. Further, the light emitting diodes LED ₁ and LED ₂ are turned on even when noise is mixed in the communication lines Lu and Lt. Therefore, even if the light emitting diodes LED ₁ and LED ₂ are turned on, it is not guaranteed that the data is normally transmitted.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a communication line status display circuit having a structure capable of displaying that data is normally transmitted and having improved display reliability. It is a thing.

[0008]

In order to achieve the above object, a plurality of slave stations are branched and connected to a master station via a communication line and a data link is formed by a polling / selecting method. Used in a communication system configured to establish, detects the presence or absence of an error in the communication line status display circuit that is provided in at least one of the master station and the slave station and that indicates that data is being transmitted normally. An error detection unit, a sequence determination unit that determines the establishment of the data link, and a communication status display unit that indicates that the communication line is normal when no error occurs and the data link is established. There is.

According to the second aspect of the present invention, the start bit and the stop bit are added before and after the fixed length data, and when one of the start bit and the stop bit of the transmission data and the reception data is detected, the transmission data is detected. A transmission / reception display unit is provided to perform display corresponding to received data.

[0010]

According to the first aspect of the present invention, the communication state indicating that the communication line is normal when no error is detected by the error detection unit and the establishment of the data link is detected by the sequence determination unit Since the display is provided,
At least when the data link is established and the conditions for establishing communication are satisfied, it is displayed on the communication status display section for the first time, and when the communication status display section shows that it is normal, Since it is guaranteed that no error has occurred due to noise etc.,
High reliability can be obtained in the display on the communication status display unit.

According to the second aspect of the present invention, when the synchronization method is the start-stop synchronization method, the transmission / reception display unit for displaying the start bit or the stop bit of the transmission data and the reception data is provided. When used in combination with the display of the communication status display section for displaying whether or not various communication is performed, it can be more surely known whether or not the data is normally transmitted. That is, since the display corresponding to the transmission data and the reception data is performed, it is possible to know whether the data is being transmitted or received.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, as compared with the circuit of FIG.
The difference is that a series circuit of a resistor R ₃ and a light emitting diode LED ₃ is connected to an output port of the processing device 21 via a buffer Bf ₃ . The processing device 21 is provided with a line buffer 23 that temporarily holds the data from the driver / receiver 22. The transmission data Tx and the reception data Rx are sequentially written in the line buffer 23, and the transmission data Tx and the reception data Rx are sequentially read from the line buffer 23. The line buffer 23 has a capacity of at least one character.
Received data Rx read from the line buffer 23
Is input to the error detection unit 24 and the presence or absence of an error is determined for each character. Here, the types of errors to be determined include parity error, overrun error, and framing error. The parity error is detected by the mismatch of the parity bits given for each character or block, and by detecting the parity error, it can be detected that there is a transmission error due to noise or the like. The overrun error is detected when the read speed is slower than the write speed of the received data Rx to the line buffer 23. Generally, one character of the received data Rx is written in the line buffer 23 and the read data is read. It occurs when the next character is received before it is sent out.
If an overrun error occurs, the data has been lost. The framing error is detected when the stop bit SP has an error. That is, as shown in FIG. 3, the data according to the present invention has one character before and after one character.
Start bit ST and stop bit SP bit by bit
It is transmitted in a start-and-stop manner by loading and
Since the stop bit SP is at the H level (logical value is 1), if it is at the L level at the position of the stop bit SP, a framing error is detected. When a framing error is detected, it can be determined that a transmission error has occurred due to noise or the like, similar to a parity error.

As described above, the error detecting section 24 detects the occurrence of the parity error, the overrun error and the framing error, thereby detecting the occurrence of the transmission error and the data loss. Therefore, when these errors do not occur, it can be judged that the transmission system is normal. Further, even when the communication speeds do not match, any error occurs, so that the communication speed mismatch can be indirectly detected. In order to more surely detect the coincidence of the communication speed, the communication speed may be determined separately.

When the error detector 24 determines that the transmission system is normal, the sequence determiner 25
It is determined whether the watch sequence is well formed. That is, it is determined whether a block has a predetermined number and has a predetermined meaning by analyzing a character group (block) composed of a plurality of characters. Generally, it is determined whether or not a block includes a polling address or a selecting address and has a predetermined format. If the monitoring sequences match, it can be considered that normal data transmission is possible, so the output port is set to the L level through the output section 26 and the light emitting diode LED ₃ is turned on. That is, the light emitting diode LED ₃ is turned on when there is no error in the transmission system and the monitoring sequences match, and it is confirmed that the data is normally transmitted by turning on the light emitting diode LED _3. It Therefore, the buffer Bf ₃ , the resistor R ₃ , and the light emitting diode LED ₃ constitute a communication state display section. Here, the error detection unit 24 and the sequence determination unit 25 can be realized by software by setting an appropriate program for performing the above operation for the microprocessor constituting the processing device 21.

On the line between the processing device 21 and the driver / receiver 22, light emitting diodes LED ₁ and LED ₂ are turned on when the start bit ST in the transmission data Tx and the reception data Rx is detected, as in the conventional configuration.
Are connected via the buffers Bf ₁ and Bf ₂ . Therefore, the light emitting diode LED ₁ is turned on during transmission, and the light emitting diode LED ₂ is turned on during reception, whereby it is possible to discriminate between the transmission and the reception. That is, the buffers Bf ₁ and Bf ₂ , the resistors R ₁ and R ₂ , and the light emitting diodes LED ₁ and LED _{2 form a} transmission / reception display unit. With the above configuration, based on the display on the display unit 20 including the transmission / reception display unit and the communication status display unit, the user can accurately know the communication status and whether or not normal communication is performed. You can check.

In the above configuration, the line buffer 23
Although the error detection unit 24 is provided in the processing device 21, the general-purpose driver / receiver 22 has a transmission buffer,
Since there is a receiver having a reception buffer and an error detection unit 24, the function of the error detection unit 24 is
It is also possible to provide only the sequence determination unit 25 in the processing device 21 by distributing the determination result in the error detection unit 24 to the processing device 21. Further, the display unit 20 includes the light emitting diodes LED ₁ to.
Only display is done by turning on / off the LED ₃ .
It is also possible to display normality / abnormality by using a display device capable of displaying characters and figures. Further, although the transmission / reception display section displays the display corresponding to the start bit ST, the display corresponding to the stop bit SP may be displayed.

[0017]

According to the first aspect of the present invention, the communication state is displayed to indicate that the communication line is normal when the error is not detected by the error detecting section and the establishment of the data link is detected by the sequence judging section. Since the display is provided,
At least when the data link is established and the conditions for establishing communication are satisfied, it is displayed on the communication status display section for the first time, and when the communication status display section shows that it is normal, Since it is guaranteed that no error has occurred due to noise etc.,
There is an advantage that high reliability can be obtained in the display on the communication status display unit.

According to the second aspect of the invention, when the synchronization method is the start-stop synchronization method, the transmission / reception display unit for displaying the start bit or the stop bit of the transmission data and the reception data is provided. When used in combination with the display of the communication status display section for displaying whether or not various communication is performed, it can be more surely known whether or not the data is normally transmitted. That is, since the display corresponding to the transmission data and the reception data is performed, there is an advantage that it is possible to know whether the data is being transmitted or received.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment.

FIG. 2 is a block circuit diagram showing an example of a communication system using the present invention.

FIG. 3 is an explanatory diagram showing a format of data used in the communication system shown in FIG.

FIG. 4 is a circuit diagram showing a conventional example.

[Explanation of symbols]

1 the central control unit 2 the central monitor board 11 Main controller 20 display unit 24 error detection unit 25 sequence determination unit Bf ₁ ~Bf ₃ buffer LED ₁ ~LED ₃ light emitting diodes R ₁ to R ₃ resistor

Claims (2)

[Claims] 1. A master station and a slave station, wherein a plurality of slave stations are branched and connected to a master station via a communication line and used in a communication system configured to establish a data link by a polling / selecting method. In a communication line status display circuit that is provided in at least one side and indicates that data is transmitted normally, an error detection unit that detects the presence or absence of an error, a sequence determination unit that determines the establishment of a data link, and an error A communication line status display circuit, comprising: a communication status display unit for displaying that the communication line is normal when the data link is established. 2. A start bit and a stop bit are added before and after a fixed length of data, and when one of the start bit and the stop bit of the transmission data and the reception data is detected, the transmission data and the reception data are respectively detected. 2. The communication line status display circuit according to claim 1, further comprising a transmission / reception display unit for performing corresponding display.