JP2006195780A - Controller and remote i/o communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cope with data communication troubles between a controller and a remote I/O apparatus, which may occur if an incompatible cable is used. <P>SOLUTION: Specified test signals are transmitted to the remote I/O apparatus 2 through a communication cable 3, and the test signals returned from the remote I/O apparatus 2 are received. A delay time from the transmission to the receiving is measured, and then data based on the delay time are compared with specified reference values. Corresponding to the comparison result, the quality of data communication situations is determined and an alarm is issued according to the quality determination. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a data communication technology, and more particularly to a remote I / O communication technology performed between a controller that controls each facility device by a facility management system and a remote I / O device that connects these facility devices at remote locations.

In equipment management systems such as buildings, factories, and plants, when equipment is installed in a remote location, the equipment is connected to a remote I / O device, and the remote I / O device and the controller have communication capability. A configuration is adopted in which connection is made via a high communication network.
In such a communication network, a dedicated remote I / O cable is used in order to maintain communication capability such as transmission characteristics and noise resistance. An Ethernet (registered trademark) cable is used as the remote I / O cable. Sometimes used.
In general, an Ethernet cable is widely marketed as a LAN cable compatible with 100BAST-T, for example, and is easier to obtain than a dedicated remote I / O cable.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
JP-A-6-204768 JP 2002-277494 A

However, in such a conventional technology, there is a problem in that, when a controller and a remote I / O device are connected using a non-conforming cable, there is a possibility that a problem occurs in data communication between the two.
In general, the dedicated remote I / O cable described above has a specified cable length based on specifications in consideration of signal attenuation and waveform distortion in accordance with its electrical characteristics and transmission method. However, since it is easy to obtain various lengths of Ethernet cables, non-conforming cables that are out of specification may be used. Therefore, if the controller and the remote I / O device are connected using such a non-conforming cable whose cable length does not meet the specifications, the delay in the communication cable increases, causing a transmission error.

In a system that transmits a large amount of data between a controller and a remote I / O device at a high speed, the controller and the remote I / O device are connected in parallel with a plurality of remote I / O cables. Become. This is because the number of core wires of the remote I / O cable is limited to 8 (4 pairs).
In this case, if individual communication cables used for parallel connection have different electrical characteristics and lengths, signal attenuation and transfer delay differ between the communication cables, which may cause transmission errors due to data synchronization shifts. Become.

If the cable is used in a severe corrosive atmosphere such as sulfide, the contact resistance increases due to deterioration of the contact portion between the connector and the cable, and there is an effect similar to the increase in the cable length. This causes a transmission error due to synchronization loss.
The present invention is intended to solve such problems, and a controller and a remote I / O communication method that can cope with a data communication failure between a controller and a remote I / O device that may occur when a nonconforming cable is used. The purpose is to provide.

  In order to achieve such an object, a controller according to the present invention is a controller that controls equipment by performing data communication with a remote I / O device that connects the equipment with a communication cable. Test signal transmission / reception means for transmitting a predetermined test signal to a remote I / O device via a cable and receiving a test signal transmitted from the remote I / O device, and a delay from the time when the test signal is transmitted to the time when it is received Delay time measuring means for measuring time and determination means for determining whether the data communication status is good or not according to a comparison result obtained by comparing data based on the delay time with a predetermined reference value.

  At this time, the test signal transmitting / receiving means simultaneously transmits a predetermined test signal to the remote I / O device via the communication cable for each of the plurality of communication cables connected in parallel with the remote I / O device. The test signal sent back from the remote I / O device may be received, and the delay time measurement means may measure the reception time difference between the test signals received by the communication cables as the delay time.

  In addition, another controller according to the present invention is connected in parallel to a remote I / O device that connects facility equipment via a plurality of communication cables, and performs parallel data communication using these communication cables simultaneously. A controller for controlling a device, which transmits a predetermined test signal to a remote I / O device for each communication cable and receives a test signal transmitted back from the remote I / O device; For each cable, the delay time measuring means for measuring the delay time from the transmission time of the test signal to the reception time, and the data sent from the remote I / O device via each communication cable via parallel data communication Data receiving means for receiving at a timing according to the delay time of the cable.

  The remote I / O communication method according to the present invention is a remote I / O communication performed by a controller that controls equipment by performing data communication with a remote I / O device that connects the equipment with a communication cable. A test signal transmitting / receiving step for transmitting a predetermined test signal to a remote I / O device via a communication cable and receiving a test signal transmitted from the remote I / O device, and a test signal transmission time point A delay time measuring step for measuring a delay time from the reception time to a reception time point, and a determination step for determining whether the data communication status is good or not according to a comparison result obtained by comparing data based on the delay time with a predetermined reference value. .

  At this time, in the test transmission step, a predetermined test signal is simultaneously transmitted to the remote I / O device via the communication cable for each of the plurality of communication cables connected in parallel with the remote I / O device. The test signal sent back from the I / O device may be received, and the delay time measurement step may measure the reception time difference between the test signals received by the communication cables as the delay time.

  In addition, another remote I / O communication method according to the present invention is connected in parallel via a plurality of communication cables with a remote I / O device for connecting equipment, and parallel data communication using these communication cables simultaneously. Is a remote I / O communication method that is performed by a controller that controls equipment by performing transmission, transmitting a predetermined test signal to the remote I / O device for each communication cable, and sending back from the remote I / O device. A test signal transmission / reception step for receiving the received test signal, a delay time measurement step for measuring a delay time from the transmission time of the test signal to the reception time for each communication cable, and a remote I / O device via each communication cable Data received via parallel data communication is received at a timing according to the delay time of each communication cable. And a receiving step.

  According to the present invention, a delay time measured from a test signal transmission time to a reception time, a delay time indicating a propagation delay time difference between communication cables, and a large variation in the delay time measured using the test signal. Depending on the situation, the data communication status and the connection status of the connector that electrically connects the communication cable are judged, so there is a large difference between the cable length that is longer than the usable cable length and other cables. Predicting transmission errors that may occur when using non-conforming cables such as communication cables, or communication cables that have started to increase in contact resistance due to deterioration in a severe corrosive atmosphere, encourages countermeasures, and prevents transmission errors. By avoiding this, normal data communication can be performed, and it is possible to cope with a data communication failure caused by a nonconforming cable.

Next, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, a controller according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a controller according to the first embodiment of the present invention.

This controller 1 is used in equipment management systems such as buildings, factories, plants, etc., and equipment equipment by performing data communication via a communication cable 3 with a remote I / O device 2 that connects equipment equipment (not shown). It is a control apparatus which controls.
The remote I / O device 2 is an interface device that relays data exchanged between the controller 1 and the facility device by performing data communication with the controller 1 and data communication with the facility device.

  In the present embodiment, the controller 1 transmits a predetermined test signal to the remote I / O device 2 via the communication cable 3 and receives the test signal transmitted back from the remote I / O device 2. Measure the delay time from the transmission time to the reception time, determine the quality of the data communication status according to the comparison result comparing the delay time with a predetermined reference value, and issue an alarm according to the failure determination It is a thing.

[controller]
First, the configuration of a controller according to the first embodiment of the present invention will be described with reference to FIG.
The controller 1 includes a clock generation circuit 10, a test circuit 11, a data transmission / reception circuit 15, a delay time measurement circuit 16, a determination circuit 17, a storage circuit 18, and a control circuit 19. These circuits are composed of predetermined signal processing circuits and logic circuits.
For example, for the control system circuits such as the delay time measurement circuit 16, the determination circuit 17, and the control circuit 19, the hardware and the program cooperate with each other by executing the program in the peripheral circuit of the CPU. You may comprise from the arithmetic processing part (not shown) to implement | achieve.

The clock generation circuit 10 generates a clock signal for synchronization used when data is transmitted and received between the controller 1 and the remote I / O device 2 via the communication cable 3, and the clock signal is used as each circuit of the controller 1. And a circuit that transmits to the remote I / O device 2 via the communication cable 3.
The test circuit 11 transmits a predetermined test signal to the remote I / O device 2 via the communication cable 3 in response to an instruction from the control circuit 19 and returns from the remote I / O device 2 in response thereto. It is a circuit for receiving a transmitted test signal.

The test circuit 11 is provided with a test signal transmission circuit 12 and a test signal reception circuit 13.
The test signal transmission circuit 12 is a circuit that transmits a predetermined test signal to the remote I / O device 2 via the communication cable 3 in accordance with an instruction from the control circuit 19.
The test signal receiving circuit 13 is a circuit that receives the test signal transmitted from the remote I / O device 2 in response to the test signal transmitted from the test signal transmitting circuit 12.

The data transmission / reception circuit 15 is a circuit that transmits / receives desired data to / from the remote I / O device 2 via the communication cable 3.
The delay time measurement circuit 16 is a circuit unit that measures the delay time from the transmission time point to the reception time point of the test signal transmitted and received by the test circuit 11.
The determination circuit 17 compares the delay time measured by the delay time measurement circuit 16 with a predetermined reference value, and performs data communication with the remote I / O device 2 using the communication cable 3 according to the comparison result. This is a circuit for determining whether the communication status is good or bad.

The storage circuit 18 includes a memory circuit and the like, and stores system information for controlling equipment and various information such as control information and programs used for control processing in the control circuit 19.
The control circuit 19 is a circuit that controls each circuit unit of the controller 1, and includes equipment control means 19A and alarm means 19B as functional means.

The equipment control means 19A sends predetermined data to the data transmission / reception circuit 15 and the communication in accordance with system information used in the equipment management system stored in the storage circuit 18 and an instruction from a host device (not shown) such as a system monitoring device. The function of transmitting to the remote I / O device 2 via the cable 3 and the data received from the remote I / O device 2 via the data transmission / reception circuit 15 and the communication cable 3 are stored in the storage circuit 18 or transmitted to the host device. It has the function to do.
When the determination result obtained by the determination circuit 17 indicates that the communication status is poor, the alarm means 19B is activated by the controller 1 by visual display using an LED (not shown) or audible display using a buzzer (not shown). It has a function of issuing an alarm to that effect or transmitting a predetermined message to a host device such as a system monitoring device.

[Remote I / O device]
Next, the configuration of the remote I / O device connected to the controller according to the first embodiment of the present invention will be described with reference to FIG.
The remote I / O device 2 is provided with a clock reception circuit 20, a signal transmission / reception circuit 21, a data transmission / reception circuit 22, and an equipment control circuit 23. These circuits are composed of predetermined signal processing circuits and logic circuits.
For example, for a control system circuit such as the equipment control circuit 23, an arithmetic processing unit (not shown) that realizes a functional unit by causing the CPU and its peripheral circuits to execute a program to cooperate the hardware and the program. You may comprise.

The clock reception circuit 20 receives a synchronization clock signal transmitted from the clock generation circuit 10 of the controller 1 via the communication cable 3 and supplies the clock signal to each circuit unit of the remote I / O device 2. It is.
The signal transmission / reception circuit 21 is a circuit that receives a test signal transmitted from the test circuit 11 of the controller 1 via the communication cable 3 and transmits the test signal back to the controller 1 via the communication cable 3.

The data transmission / reception circuit 22 is a circuit that transmits / receives data to / from the data transmission / reception circuit 15 of the controller 1 via the communication cable 3.
The equipment control circuit 23 transmits data from the controller 1 received by the data transmission / reception circuit 22 to equipment equipment (not shown) externally connected to the remote I / O device 2 and also sends data from the equipment equipment. It is a circuit that relays various data exchanged between the controller 1 and the equipment by receiving and transmitting the data from the data transmission / reception circuit 22 to the controller 1.

[Operation of First Embodiment]
Next, the operation of the controller according to the first embodiment of the present invention will be described with reference to FIGS.
FIG. 2 is a flowchart showing cable check processing of the controller according to the first embodiment of the present invention. FIG. 3 is a signal waveform diagram showing a delay time measuring operation of the controller according to the first embodiment of the present invention.

The control circuit 19 of the controller 1 executes the cable confirmation process of FIG. 2 periodically or in response to an external instruction.
First, the control circuit 19 starts transmission of a predetermined test signal to the remote I / O device 2 via the communication cable 3 by the test signal transmission circuit 12 of the test circuit 11 (step 100), and the delay time measurement circuit 16, the measurement of the delay time required for the test signal to reciprocate between the remote I / O device 2 via the communication cable 3 is started (step 101).

On the other hand, the remote I / O device 2 receives the test signal from the controller 1 by the signal transmission / reception circuit 21 and transmits the test signal back to the controller 1.
The test circuit 11 of the controller 1 waits for the arrival of the test signal transmitted from the remote I / O device 2 by the test signal receiving circuit 13 after transmitting the test signal (step 102). In response to the start of reception of the test signal at (step 102: YES), measurement of the delay time in the delay time measurement circuit 16 is terminated (step 103).

For example, as shown in FIG. 3, when transmission of a test signal is started at time T1, and reception of the test signal is started at time T2, the difference t = T2-T1 between these times T2 and T1 is Measured as delay time.
The delay time t may be measured by sampling each signal indicating the start of test signal transmission and the start of test signal reception from the test circuit 11 by the delay time measurement circuit 16 at high speed. You may measure. Or you may measure with the internal timer of CPU.

Subsequently, the control circuit 19 of the controller 1 compares the data based on the delay time measured by the delay time measuring circuit 16, here the delay time itself and a predetermined reference value by the determination circuit 17, and according to the comparison result. Whether the communication status of the data communication with the remote I / O device 2 using the communication cable 3 is good or not is determined (step 104).
Generally, the propagation delay time of an electrical signal in this type of communication cable is, for example, about 5 ns per meter, and an upper limit value and a lower limit value may be set according to the cable length that can be used as the communication cable 3.

Here, when the measured delay time is not less than the upper limit value or less than the lower limit value and indicates a poor communication state (step 104: YES), the communication cable 3 connecting the controller 1 and the remote I / O device 2 is It is determined that the cable length is longer than the appropriate cable length, and the alarm means 19B issues a warning to that effect using a visual display using an LED (not shown) or an audible display using a buzzer (not shown), or a predetermined Is sent to a higher-level device such as a system monitoring device (step 105), and the series of cable confirmation processing ends.
Further, when the measured delay time is not more than the upper limit value and not less than the lower limit value and indicates a good communication state (step 104: NO), the communication cable 3 connecting the controller 1 and the remote I / O device 2 Determines that the cable length is appropriate, and ends the series of cable confirmation processes without issuing an alarm.

  As described above, in the present embodiment, a predetermined test signal is transmitted to the remote I / O device 2 via the communication cable 3, and the test signal transmitted from the remote I / O device 2 is received, The delay time from the transmission time to the reception time is measured, the quality of the data communication situation is judged according to the comparison result comparing the data based on the delay time and a predetermined reference value, and an alarm is given according to the failure judgment When the communication cable 3 is longer than the usable cable length, an alarm can notify the operator that a data communication failure due to the communication cable length may occur.

  Therefore, it is possible to predict in advance a data communication failure that may occur when a nonconforming cable exceeding the specified length is used as a communication cable for connecting the controller 1 and the remote I / O device 2, and an appropriate response can be promoted. .

In the above description, the case where only one communication cable 3 is used has been described as an example. However, when the controller 1 and the remote I / O device 2 are connected using a plurality of communication cables 3, the communication cable is used. Every three, the delay time is measured using the test signal described above, the quality of the data communication status is determined according to the comparison result with the reference value, and an alarm is issued according to the determination of the failure.
At this time, the test circuit 11 may be provided for each communication cable 3, but a plurality of communication cables 3 may also be used as one test circuit 11 and may be sequentially measured for each communication cable. The circuit configuration can be simplified.

[Second Embodiment]
Next, a controller according to the second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram showing a configuration of a controller according to the second embodiment of the present invention. The same reference numerals are given to the same or equivalent parts as those in FIG.

In the first embodiment described above, it may occur when the communication cable 3 exceeds the specified length by issuing an alarm according to the comparison result between the data based on the delay time measured using the test signal and the reference value. The case of dealing with data communication problems was explained.
In the present embodiment, an alarm is generated according to a comparison result between data based on a delay time indicating a propagation delay difference of a test signal in a plurality of communication cables connecting the controller 1 and the remote I / O device 2 in parallel and a reference value. A case will be described in which a data communication failure that may occur according to the difference in the length of the communication cable 3 is dealt with.

In the controller 1 according to the present embodiment, the controller 1 and the remote I / O device 2 are connected in parallel by two communication cables 3A and 3B, as compared with the first embodiment (see FIG. 1) described above. Yes. Accordingly, the controller 1 is provided with test circuits 11A and 11B and a data transmission / reception circuit 15 for each of the communication cables 3A and 3B.
Further, the remote I / O device 2 is provided with signal transmission / reception circuits 21A, 2AB and data transmission / reception circuits 22A, 22B for each of the communication cables 3A, 3B. Other configurations are the same as those of the first embodiment described above, and a detailed description thereof is omitted here.

[Operation of Second Embodiment]
Next, the operation of the controller according to the second embodiment of the present invention will be described with reference to FIGS.
FIG. 5 is a flowchart showing cable check processing of the controller according to the second embodiment of the present invention. FIG. 6 is a signal waveform diagram showing a delay time measurement operation of the controller according to the second embodiment of the present invention.

The control circuit 19 of the controller 1 executes the cable confirmation process of FIG. 5 periodically or in response to an external instruction.
First, the control circuit 19 simultaneously starts transmitting predetermined test signals to the remote I / O device 2 via the communication cables 3A and 3B by the test signal transmission circuits 12A and 12B of the test circuits 11A and 11B (step 110). ).

On the other hand, the remote I / O device 2 receives the test signal from the controller 1 via the communication cables 3A and 3B by the signal transmission / reception circuits 21A and 21B and receives the test signal via the communication cables 3A and 3B. Send back to 1.
After transmitting the test signal, the test circuits 11A and 11B of the controller 1 stand by for the arrival of the test signal returned from the remote I / O device 2 by the test signal receiving circuit 13 (step 111).

When reception of a test signal is started by the test signal receiving circuits 13A and 13B via either one of the communication cables 3A and 3B (step 111: YES), the communication cables 3A and 3B are transmitted by the delay time measuring circuit 16. Measurement is started for a delay time indicating a propagation delay difference at (step 112).
Thereafter, when reception of the test signal is started by the test signal receiving circuits 13A and 13B via the other of the communication cables 3A and 3B (step 113: YES), measurement of the delay time in the delay time measuring circuit 16 is ended. (Step 114).

For example, as shown in FIG. 6, the transmission of the test signal is simultaneously started at the time T1 in the communication cables 3A and 3B, the reception of the test signal is started via the communication cable 3A at the subsequent time T2, and the time after that When reception of the test signal is started via the communication cable 3B at T3, a time difference T3-T2 between these times T3 and T2 is measured as a desired delay time t.
The delay time t may be measured by sampling each signal indicating the start of test signal transmission and the start of test signal reception from the test circuit 11 by the delay time measurement circuit 16 at high speed. You may measure. Or you may measure with the internal timer of CPU.

Subsequently, the control circuit 19 of the controller 1 compares the data based on the delay time measured by the delay time measuring circuit 16, here the delay time itself and a predetermined reference value by the determination circuit 17, and according to the comparison result. Whether the communication status of the data communication with the remote I / O device 2 using the communication cable 3 is good or not is determined (step 115).
In general, in this type of equipment management system, when data communication is performed between a controller 1 and a remote I / O device 2 using a plurality of communication cables simultaneously in parallel, at a timing synchronized with a common clock, The signal received via each communication cable is captured. Therefore, a reference value may be set according to an allowable value for a propagation delay difference between these communication cables.

Here, when the measured delay time exceeds the reference value and indicates a poor communication status (step 115: YES), the cable length between the communication cables 3 that connect the controller 1 and the remote I / O device 2 in parallel is determined. Judge that the difference is large.
In this case, the alarm means 19B issues a warning to that effect using a visual display using an LED (not shown) or an audible display using a buzzer (not shown), or a predetermined message. The data is transmitted to a higher-level device such as a system monitoring device (step 116), and the series of cable confirmation processing ends.

  If the measured delay time is equal to or less than the reference value and the communication status is good (step 115: NO), the cable length between the communication cables 3 that connect the controller 1 and the remote I / O device 2 in parallel is determined. It is determined that the variation is small and appropriate, and a series of cable confirmation processes are terminated without issuing an alarm.

  Thus, in this embodiment, each of the plurality of communication cables 3A and 3B connected in parallel with the remote I / O device 2 is connected to the remote I / O device 2 via the communication cables 3A and 3B. A predetermined test signal is transmitted at the same time, a test signal sent back from the remote I / O device 2 is received, and a difference in reception time of each test signal received by each communication cable is measured as a delay time. Since the quality of the data communication status is determined according to the comparison result comparing the data based on the delay time with a predetermined reference value, and an alarm is issued according to the failure determination, the length of each communication cable 3A, 3B When the difference is large, it is possible to notify the operator that there is a possibility that a data communication failure due to a variation in the communication cable length may occur due to an alarm.

  Therefore, it is possible to predict in advance data communication problems that may occur when non-conforming cables having different lengths are used as a plurality of communication cables that connect the controller 1 and the remote I / O device 2 in parallel, and promote appropriate measures. be able to.

  In the above, the case where two communication cables 3 are used has been described as an example. However, when the controller 1 and the remote I / O device 2 are connected in parallel using three or more communication cables 3, What is necessary is just to measure the difference (maximum difference) between the time of receiving the received signal earliest and the time of receiving the latest received signal among the communication cables 3 as the delay time.

  In the present embodiment, the test signals are simultaneously transmitted through the communication cables 3A and 3B, and the reception timing difference between these test signals is measured as a delay time. Therefore, the test signal is transmitted only once. The desired delay time can be measured directly, the communication cable confirmation process can be performed in a very short time, and the influence on the process related to the control of the normal equipment in the controller 1 and the remote I / O device 2 is minimized. Can be suppressed.

Note that the propagation delay time between the communication cables 3A and 3B is measured by the delay time measurement circuit 16 for each communication cable 3A and 3B, from the transmission time to the reception time of the test signal. The desired delay time may be calculated from the difference (maximum difference) between these propagation delay times.
At this time, the test circuit 11 may be provided for each communication cable 3, but a plurality of communication cables 3 may also be used as one test circuit 11 and may be sequentially measured for each communication cable. The circuit configuration can be simplified.

[Third Embodiment]
Next, a controller according to a third embodiment of the present invention will be described.
In the second embodiment described above, the comparison result between the reference data and the data based on the delay time indicating the propagation delay difference of the test signal in the plurality of communication cables connecting the controller 1 and the remote I / O device 2 in parallel. The case where an alarm is issued in response to the above has been described.

In the present embodiment, the delay time required for the propagation of the test signal is measured for each communication cable, and the data from the remote I / O device 2 is received at the reception timing corresponding to the data based on the delay time. A case of dealing with a data communication failure that may occur according to the difference in the length of the communication cable 3 will be described.
The controller 1 according to the present embodiment has the same configuration as that of the second embodiment (see FIG. 4) described above, and detailed description thereof is omitted here.

[Operation of Third Embodiment]
Next, the operation of the controller according to the third embodiment of the present invention will be described with reference to FIGS.
FIG. 7 is a flowchart showing cable check processing of the controller according to the third embodiment of the present invention. FIG. 8 is a signal waveform diagram showing a delay time measurement operation of the controller according to the third embodiment of the present invention. FIG. 9 is a signal waveform diagram showing data reception timing of the controller according to the third embodiment of the present invention.

The control circuit 19 of the controller 1 executes the cable confirmation process of FIG. 7 periodically or in response to an external instruction.
First, the control circuit 19 simultaneously starts transmission of a predetermined test signal to the remote I / O device 2 via the communication cables 3A and 3B by the test signal transmission circuits 12A and 12B of the test circuits 11A and 11B (step S1). 120) The delay time measurement circuit 16 starts measuring the delay time required for the test signal to reciprocate between the remote I / O device 2 for each of the communication cables 3A and 3B (step 121).

On the other hand, the remote I / O device 2 receives the test signal from the controller 1 via the communication cables 3A and 3B by the signal transmission / reception circuits 21A and 21B and receives the test signal via the communication cables 3A and 3B. Send back to 1.
After transmitting the test signal, the test circuit 11 of the controller 1 waits for the arrival of the test signal returned from the remote I / O device 2 by the test signal receiving circuits 13A and 13B (step 122).
Then, in response to the reception of the test signal by the test signal receiving circuits 13A and 13B (step 122: YES), the measurement of the delay time by the delay time measuring circuit 16 relating to the communication cables 3A and 3B is ended (step 123). .

For example, as shown in FIG. 8, the transmission of the test signal is started simultaneously at the time T1 by the communication cables 3A and 3B, and the reception of the test signal is started by the test signal receiving circuit 13A of the communication cable 3A at the subsequent time T2. In this case, the difference ta = T2−T1 between the time T2 and the time T1 is measured as the delay time.
Similarly, when reception of a test signal is started by the test signal receiving circuit 13B of the communication cable 3B at time T3, a difference tb = T3−T1 between these times T3 and T1 is measured as a delay time.

  The delay times ta and tb may be measured by sampling the signals indicating the start of test signal transmission and the start of test signal reception from the test circuit 11 by the delay time measurement circuit 16 at a high speed. May be used to measure. Or you may measure with the internal timer of CPU.

  Thus, after the measurement of the delay time for all the communication cables 3A and 3B is completed (step 124: YES), the data based on the delay time measured for each communication cable 3A and 3B, here based on the delay time itself. The reception timing for the data from the remote I / O device 2 in the data transmission / reception circuits 15A and 15B of the communication cables 3A and 3B is set (step 125), and the series of cable confirmation processing ends.

  Therefore, as shown in FIG. 9, in the data transmission / reception circuits 15A and 15B, the delay times ta and tb measured by the respective communication cables 3A and 3B with respect to the reference clock signal supplied from the clock generation circuit 10. The reception timings 41A and 41B delayed by the delay amounts da and db corresponding to are set, and data from the remote I / O device 2 is received based on these reception timings 41A and 41B.

  At this time, for example, in the reference clock signal before the reception timing adjustment, the reception data 41A and 42B are received and latched (latched) at the falling edge of the time T1, so that if the cable length is relatively long, for example, the reception data 42B Delay increases and reception cannot be performed normally.

On the other hand, after the adjustment, the received data 41A is received by the data transmission / reception circuit 15A based on the reception timing 42A delayed by the delay amount da from the time T1, and the reception timing 42B delayed by the delay amount db from the time T1. On the basis of the received data, the data transmission / reception circuit 15A receives and takes in the received data 41A.
Therefore, the reception data 42A and 42B can be normally received and taken in at an appropriate timing when the waveform is stable.

  Thus, in this embodiment, each of the plurality of communication cables 3A and 3B connected in parallel with the remote I / O device 2 is connected to the remote I / O device 2 via the communication cables 3A and 3B. A predetermined test signal is transmitted at the same time, a test signal sent back from the remote I / O device 2 is received, and a delay time from the transmission time of the test signal to the reception time is measured for each communication cable. Since the reception timing for the data from the remote I / O device 2 in the data transmission / reception circuits 15A and 15B of the communication cables 3A and 3B is set based on the data based on the delay time measured for the communication cable. Even when the length of the cables 3A and 3B is different, remote I / O is performed at an appropriate timing for each communication cable. It receives data from location 2.

  Therefore, it is possible to avoid data communication problems that may occur when non-conforming cables having different lengths are used as a plurality of communication cables for connecting the controller 1 and the remote I / O device 2 in parallel, and normal data communication can be realized. .

In the present embodiment, the test signals are simultaneously transmitted through the communication cables 3A and 3B, and the reception timing difference between these test signals is measured as a delay time. Therefore, the test signal is transmitted only once. A desired delay time can be measured for each communication cable.
Thereby, the confirmation process of the communication cable can be performed in an extremely short time, and the influence on the process related to the control of the normal equipment in the controller 1 and the remote I / O device 2 can be suppressed to the minimum.

Note that the propagation delay time between the communication cables 3A and 3B is measured by the delay time measurement circuit 16 for each communication cable 3A and 3B, from the transmission time to the reception time of the test signal. May be.
At this time, the test circuit 11 may be provided for each communication cable 3, but a plurality of communication cables 3 may also be used as one test circuit 11 and may be sequentially measured for each communication cable. The circuit configuration can be simplified.

[Fourth Embodiment]
Next, a controller according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a block diagram showing a configuration of a controller according to the fourth embodiment of the present invention. The same reference numerals are given to the same or equivalent parts as those in FIG.

In the first embodiment described above, a case has been described in which an alarm is issued according to a comparison result between data based on a delay time measured using a test signal and a reference value.
In this embodiment, the variation value of each delay time measured using the test signal is used as the data based on the delay time, and the connection state of the communication cable based on the comparison result between the variation value and the allowable value (reference value). A case will be described in which a data communication failure that may occur in response to an increase in contact resistance between the connector and the communication cable is dealt with.

In the controller 1 according to the present embodiment shown in FIG. 10, a determination means 19 </ b> C is newly provided in the control circuit 19 compared to the first embodiment (see FIG. 1) described above. This determination means 19C is a functional means for diagnosing the connection status of the communication cable 3 based on the variation of each delay time measured using the test signal. Further, the determination circuit 17 is not necessary.
In the controller 1 of FIG. 10, the test circuit 11 is provided with a threshold value determination circuit 14, but this is not an essential configuration. The threshold value determination circuit 14 is a circuit that compares and determines the amplitude value of the test signal transmitted from the remote I / O device 2 and a predetermined threshold voltage. Other configurations are the same as those of the first embodiment described above, and a detailed description thereof is omitted here.

[Operation of Fourth Embodiment]
Next, with reference to FIGS. 11 and 12, the operation of the controller according to the fourth embodiment of the present invention will be described.
FIG. 11 is a flowchart showing cable check processing of the controller according to the fourth embodiment of the present invention. FIG. 12 is an explanatory diagram showing variation in delay time measured by the controller according to the fourth embodiment of the present invention.

The control circuit 19 of the controller 1 executes the cable confirmation process of FIG. 5 periodically or in response to an external instruction.
First, the control circuit 19 measures the delay time from the transmission time of the test signal to the reception time by executing the same processing as the steps 100 to 103 of the cable confirmation processing of FIG. 2 described above (step 130). The obtained delay times are sequentially stored in the storage circuit 18 (step 131).

Next, a variation value of each delay time stored in the storage circuit 18, for example, a standard deviation, a range (range), a variance value, etc. of each delay time measured within the most recent predetermined period. A statistic indicating the magnitude is calculated (step 132).
Then, the connection status of the connector (not shown) for electrically connecting the communication cable 3 to the controller 1 or the remote I / O device 2 by comparing this variation value with a predetermined allowable value (reference value). Is determined (step 133).

Generally, in this type of equipment management system, when the communication cable 3 is connected to the controller 1 or the remote I / O device 2, a modular jack type connector is provided on the controller 1 or the remote I / O device 2, and the communication cable 3 By inserting a modular plug provided at the end point into the connector, for example, contact points plated with gold are brought into contact with each other, and both are electrically connected.
Normally, the contact resistance between these contacts is extremely low, but in a plant where the corrosive environment due to sulfide is severe, an insulating corrosion product appears from the base metal on the plating, causing an increase in contact resistance. When the contact point deteriorates and the contact resistance increases in this way, the rounding of the signal waveform becomes large, which causes a transmission error due to delay or synchronization shift.

At this time, if the contact point deteriorates, the insulating corrosion product on the plating is destroyed due to vibration of the device or communication cable, or micro movement or displacement due to temperature change, etc. The contact resistance of the contact changes greatly, and the variation value of the delay time of the test signal also increases.
Therefore, a relationship between the error rate of data communication performed between the controller 1 and the remote I / O device 2 and the variation value of the delay time is obtained in advance, and an allowable value for the variation value of the delay time is set based on this relationship. You just have to.

Here, when the calculated variation value of the delay time exceeds the allowable value and indicates a poor connection state of the communication cable 3 (step 133: YES), the contact between the communication cable 3 and the connector may be deteriorated. It is judged that is high. For example, when the variation value calculated at the measurement timing TS in FIG. 12 exceeds the allowable value, it is determined that there is a high possibility that the contact has deteriorated.
In this case, the alarm means 19B issues a warning to that effect using a visual display using an LED (not shown) or an audible display using a buzzer (not shown), or system monitoring a predetermined message. The data is transmitted to a higher-level device such as a device (step 134), and the series of cable confirmation processing ends.

  Further, when the measured delay time is equal to or less than the allowable value and the connection status of the communication cable 3 is good (step 133: NO), the possibility that the contact between the communication cable 3 and the connector has deteriorated is low. Judgment is made, and a series of cable confirmation processes are terminated without issuing an alarm.

  Thus, in the present embodiment, a predetermined test signal is transmitted to the remote I / O device 2 via the communication cable 3 connected to the remote I / O device 2, and the remote I / O device 2 receives the test signal sent back from 2 and measures the delay time from the transmission time to the reception time of the test signal, and electrically connects the communication cable 3 based on the magnitude of the variation in the delay time. Since the connection status of the connector to be diagnosed is diagnosed, it is possible to diagnose the possibility that a transmission error occurs due to the synchronization shift due to the deterioration of the contact of the connector.

  Therefore, if the communication cable that connects the controller 1 and the remote I / O device 2 is used in a severe corrosive atmosphere and the contacts have deteriorated, it is possible to predict in advance data communication failures that can occur and take appropriate measures. Can be urged.

In the above description, the case where only one communication cable 3 is used has been described as an example. However, when the controller 1 and the remote I / O device 2 are connected using a plurality of communication cables 3, the communication cable is used. Every three, the delay time is measured using the test signal described above, the quality of the data communication status is determined according to the comparison result with the reference value, and an alarm is issued according to the determination of the failure.
At this time, the test circuit 11 may be provided for each communication cable 3, but a plurality of communication cables 3 may also be used as one test circuit 11 and may be sequentially measured for each communication cable. The circuit configuration can be simplified.

In the present embodiment, the case of diagnosing the connection state at the connector that electrically connects the communication cable 3 based on the variation value of the delay time has been described. However, instead of the variation value of the delay time, the test circuit 11 performs the test. The connection status at the connector may be diagnosed based on the threshold value obtained by the threshold value determination circuit 14.
In this case, the threshold determination circuit 14 increases the contact resistance of the connector by comparing and determining the amplitude value of the test signal transmitted from the remote I / O device 2 with a predetermined threshold voltage. Determine presence or absence. Then, the determination means 19C of the control circuit 19 diagnoses the connection status at the connector based on the determination presence / absence from the threshold determination circuit 14.

As a result, similarly to the case where the variation value of the delay time is used, it is possible to diagnose the possibility that a transmission error occurs due to the synchronization shift due to the deterioration of the contact of the connector. Moreover, it is not necessary to stop the apparatus and separately measure the contact resistance of the cable offline to measure the deterioration, and it is possible to monitor the deterioration of the communication cable online while performing the equipment control while the controller 1 is operating.
The amplitude of the test signal is attenuated not only by increasing the contact resistance at the connector but also by increasing the cable length of the communication cable 3. Therefore, not only the data communication failure caused by the deterioration of the contact of the connector but also the data communication failure that may occur when a communication cable exceeding the specified length is used can be predicted in advance, and an appropriate response can be promoted.

In the first to third embodiments described above, the case where the delay time itself is used as the data based on the delay time has been described as an example. However, the present invention is not limited to this, and the measurement is repeated several times. Statistics such as average, moving average, variance, maximum, and minimum calculated from a plurality of delay times obtained in this manner may be used as data based on the delay time.
In the first to third embodiments described above, the determination circuit 17 is provided separately from the control circuit 19 to compare the data based on the delay time with the reference value. 17 may be realized by the functional means of the control circuit 19 as in the determination means 19C in the fourth embodiment.

It is a block diagram which shows the structure of the controller concerning the 1st Embodiment of this invention. It is a flowchart which shows the cable confirmation process of the controller concerning the 1st Embodiment of this invention. It is a signal waveform diagram which shows the delay time measurement operation | movement of the controller concerning the 1st Embodiment of this invention. It is a block diagram which shows the structure of the controller concerning the 2nd Embodiment of this invention. It is a flowchart which shows the cable confirmation process of the controller concerning the 2nd Embodiment of this invention. It is a signal waveform diagram which shows the delay time measurement operation | movement of the controller concerning the 2nd Embodiment of this invention. It is a flowchart which shows the cable confirmation process of the controller concerning the 3rd Embodiment of this invention. It is a signal waveform diagram which shows the delay time measurement operation | movement of the controller concerning the 3rd Embodiment of this invention. It is a signal waveform diagram which shows the data reception timing of the controller concerning the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the controller concerning the 4th Embodiment of this invention. It is a flowchart which shows the cable confirmation process of the controller concerning the 4th Embodiment of this invention. It is explanatory drawing which shows the dispersion | variation in the delay time measured with the controller concerning the 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Controller, 10 ... Clock generation circuit, 11 ... Test circuit, 12 ... Test signal transmission circuit, 13 ... Test signal reception circuit, 14 ... Threshold judgment circuit, 15 ... Data transmission / reception circuit, 16 ... Delay time measurement circuit, DESCRIPTION OF SYMBOLS 17 ... Determination circuit, 18 ... Memory circuit, 19 ... Control circuit, 19A ... Equipment control means, 19B ... Alarm means, 19C ... Determination means, 2 ... Remote I / O device, 20 ... Clock reception circuit, 21 ... Signal transmission / reception circuit 22 ... Data transmission / reception circuit, 23 ... Equipment control circuit, 3, 3A, 3B ... Communication cable.

Claims (6)

A controller that controls the equipment by performing data communication with a remote I / O device that connects the equipment with a communication cable;
A test signal transmitting / receiving means for transmitting a predetermined test signal to the remote I / O device via the communication cable and receiving a test signal transmitted from the remote I / O device;
A delay time measuring means for measuring a delay time from the transmission time of the test signal to the reception time;
A controller comprising: determination means for determining whether the data communication status is good or not according to a comparison result obtained by comparing the data based on the delay time with a predetermined reference value. The controller of claim 1,
The test signal transmitting / receiving means simultaneously transmits a predetermined test signal to the remote I / O device via the communication cable for each of the plurality of communication cables connected in parallel with the remote I / O device, Receiving a test signal sent back from the remote I / O device;
The controller, wherein the delay time measuring means measures a difference in reception time of each test signal received by each communication cable as a delay time. A controller for controlling the facility equipment by performing parallel data communication using a parallel connection with a remote I / O device for connecting the equipment with a plurality of communication cables simultaneously using the communication cables,
Test signal transmitting / receiving means for transmitting a predetermined test signal to the remote I / O device for each communication cable and receiving a test signal transmitted from the remote I / O device;
Delay time measuring means for measuring a delay time from the transmission time of the test signal to the reception time for each communication cable;
Data receiving means for receiving data sent from the remote I / O device via parallel communication via each communication cable at a timing corresponding to the delay time of each communication cable; controller. A remote I / O communication method performed by a controller that controls the facility equipment by performing data communication with a remote I / O device that connects the equipment with a communication cable,
A test signal transmitting / receiving step of transmitting a predetermined test signal to the remote I / O device via the communication cable and receiving a test signal transmitted from the remote I / O device;
A delay time measuring step of measuring a delay time from the transmission time of the test signal to the reception time;
A remote I / O communication method comprising: a determination step of determining whether the data communication status is good or not according to a comparison result obtained by comparing the data based on the delay time and a predetermined reference value. The remote I / O communication method according to claim 4,
The test transmission step simultaneously transmits a predetermined test signal to the remote I / O device via the communication cable for each of a plurality of communication cables connected in parallel with the remote I / O device, Receive the test signal sent back from the remote I / O device,
In the remote I / O communication method, the delay time measurement step measures a reception time difference between test signals received by the communication cables as a delay time. A remote I / O device connected to a facility device is connected in parallel via a plurality of communication cables, and the remote I is performed by a controller that controls the facility device by performing parallel data communication using these communication cables simultaneously. / O communication method,
A test signal transmission / reception step of transmitting a predetermined test signal to the remote I / O device for each communication cable and receiving a test signal transmitted from the remote I / O device;
A delay time measuring step for measuring a delay time from the transmission time of the test signal to the reception time for each of the communication cables;
A data receiving step of receiving data transmitted from the remote I / O device via parallel communication via each communication cable at a timing corresponding to a delay time of each communication cable. Remote I / O communication method.

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