JP2001024673A - Data communication system and data input/output unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the collision of data frames transmitted from plural input and output units connected in a multi-drop format to a PLC device, using a simple constitution. SOLUTION: Different offset values are previously applied to data input/ output output units 421-42n and 431-43n. The plural data input and output units 421-42n and 431-43n successively transmit data frames with each fixed time difference (a transmission interval time × each offset value) according to transmission request commands which are communicated simultaneously from the PLC device 45.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitably applied to a dam control system and the like, and performs data communication between a control device such as a programmable controller (hereinafter, PLC) device and a data input / output unit. And a data input / output unit.

[0002]

2. Description of the Related Art Conventionally, in a dam control system that controls the opening and closing of a plurality of gates (sluice gates), a plurality of data input / output units are connected to a PLC device, and input / output between the PLC device and the data input / output unit is performed. In addition to sending and receiving data to be output, display of dam information on the display panel and console through the data input / output unit, output of chime sound at gate operation (open / close output), output of alarm sound related to dam information,
The operator inputs the switches on the console.

[0003] In the case of performing such data input / output, a PLC and a data input / output unit are used to reduce a material cost and a wiring man-hour of a communication line cable between the PLC device and the data input / output unit and to improve a hardware mounting efficiency. Various connection methods and communication methods have been adopted between the input / output units.

FIG. 14 is a block diagram showing a configuration of a conventional data communication system 1. As shown in FIG.

[0005] The data communication system 1 shown in FIG.
Basically, it comprises a PLC device 14 and a plurality of data input / output units 121 to 12n connected to the PLC device 14 via a cable 5.

The PLC device 14 is provided on a motherboard (not shown) with the PLC unit 11 and a communication I / F (interface).
The unit 13 is mounted.

[0007] The PLC section 11 has a
A U unit, a power supply unit, an I / O unit, and the like are mounted.

The communication I / F unit 13 is connected to the PLC device 1
And the data input / output units 121 to 12n connected to the communication I / F unit 13 via the cable 5 and P
This is for performing communication with the LC unit 11.

The communication I / F unit 13 is one type of a unit constituting the PLC device 14, and is generally a PLC.
Although included in the category of the C device 14, a unit group excluding the communication I / F unit 13 is referred to as a PLC unit 11 here for ease of understanding.

The communication I / F unit 13 and the data input / output units 121 to 12n are connected by a cable 5 in a current mode (circulation mode), and exchange data by asynchronous data communication. The data input / output units 121 to 12n are roughly classified into a data input unit mainly for inputting data and a data output unit mainly for output of data. In the example of FIG. 14, for the sake of convenience, the data input / output unit 121 is used for convenience.
Is a data input unit, and the data input / output unit 122 is a data output unit.

The console 2 and the like are connected to the data input / output unit 121 as a data input unit via a cable, and the state of switches and the like on the console 2 is controlled by the data input / output unit 121 and the communication I / F unit 13. Is sent to the PLC unit 11 via the.

On the other hand, the data input / output unit 122 as a data output unit is connected to the display panel 4 via a cable.
And the console are connected, and the information of the PLC unit 11 is
The data is displayed on the display panel 4 or the console through the data input / output unit 122 through the / F unit 13.

FIG. 15 shows a data sequence Dp for explaining a data communication system between the communication I / F unit 13 and the data input / output units 121 to 12n in the conventional data communication system 1 shown in FIG. .

In the data sequence Dp, the "synchronization code" is a portion where one or more bits and all the bits are set to 1 to indicate the start of the cycle transmission of the data sequence Dp (11 in this example). bit). In FIG. 15, “empty”
Is a part for distinguishing a set of adjacent addresses and data, and is a part where 4 bits or more and all bits are set to 1.

Further, the data string Dp includes an 11-bit address indicating the address of the data input / output units 121 to 12n, and the data input / output unit 121 of the address.
12n is included.

In the data input / output units 121 to 12n, addresses of data input / output by the data input / output units 121 to 12n are set by a dip switch or the like (in general, a plurality of addresses can be set).

In this case, the communication I / F unit 13 serves as a master station, and cyclically transmits addresses 0 to n and data following each of the addresses in the data format shown in FIG. Note that, in the data string Dp, the address and the data are a start bit, a data bit, and a parity bit, respectively.
It has a total of 11 bits, one bit and one stop bit.

For example, if the data of the address received by the data input / output unit 121 constituting the data input / output units 121 to 12n during the circulation of the data string Dp is data input from a switch of the console 2, etc. ,
In the data Dp transmitted cyclically, the data part of the address corresponding to the data input / output unit 121 is replaced with the latest input data.

If the data of the address received by the data input / output unit 122 is, for example, data displayed by the data input / output unit 122 on the display panel 4 or the console, the data input / output unit 122 outputs the data. Is output to the display panel 4 or the console.

FIG. 16 is a block diagram showing a configuration of a data communication system 6 as another example to which a conventional data communication system is applied. In the data communication system 6, a plurality of data input / output units 321 to 32 n are connected via a signal line 7 to a general-purpose communication I / F unit 33, for example, an RS-
Multi-drop connection to 232C I / F unit,
The PLC unit 31 exchanges data with the data input / output units 321 to 32n via the general-purpose communication I / F unit 33.

[0021]

However, FIG.
In the example data communication system 1, the data input / output units 121 to 12 n output the data in the data string transmitted cyclically to the display panel 4 and the console 2 as they are, so that the data is displayed on the PLC unit 11. It is necessary to perform on / off switching of data flicker and on / off of a warning sound, and it is necessary to increase the cyclic transmission speed of the communication I / F unit 13 and the data input / output units 121 to 12n. .

Specifically, for example, when the ON / OFF cycle period of the alarm sound is set to 50 msec and the number of data to be transmitted cyclically is 256, (address 11 bits + data 11 bits + free space) 8 bits)
× 256 + 11 bits of synchronization code = 7691 bits,
Since it must be transmitted within 50 msec, 15
A data transmission speed of 4 Kbps (7691 bits / an integer obtained by rounding up the decimal point of the quotient of 50 ms) or more is required.

For this reason, it is necessary to implement most of the functions of the cyclic transmission by a hardware mechanism.
There is a problem that hardware cost is high.

Various processes relating to data display and data input to the PLC unit 11 or the communication I / F unit 13 are also provided.
For example, it is necessary to install a chattering prevention function for input data, a blank control / flicker control for display data, a chime-on control at the time of gate operation, an alarm sound control for dam information, and the like, which increases the processing load of the PLC device 14. There are also problems.

Further, each of the data input / output units 121 to 121
12n uses a dedicated hardware mechanism for its communication, so it is difficult to connect it to a general-purpose personal computer or the like.
The use frequency of is limited. In other words, the data input / output units 121 to 12n are not general-purpose products but special-purpose products.

On the other hand, in the data communication system 6 of FIG. 16, since the PLC unit 31 performs general-purpose serial communication via the communication I / F unit 33, one communication I / F
The unit 33 includes a number of data input / output units 321 to 3
2n can be connected in a multi-drop manner, but a plurality of data input / output units 321 to 32 are provided.
Each of n is a slave station, and the communication I / F unit 33 as a master station has a right to transmit data and creates a communication protocol, and requires a complicated program for analyzing a returned response. There is a problem.

In the dam control system, when an abnormality occurs in various control devices for controlling the dam, or when the water level of the dam or the water level of the river reaches a specified value or more, the status is displayed. It must be output as warning information to the panel 4 or the like. In general, several types of alarm output formats (alarm output types) are used depending on the importance of the content of the alarm.

FIGS. 17 and 18 show alarm output types Aa and Ab as examples. The data input / output units 321 to 321 notified of the occurrence of the alarm factor from the PLC unit 31 at time t0.
32n sends control data of a display lamp and control data of an alarm sound to the display panel 4. On the display panel 4, an alarm is sounded at a relatively low fixed period until time t1,
When the alarm sound stop switch on the display panel 4 is depressed, the sounding is stopped.

On the other hand, the display lamp starts flickering at time t0, and is switched to continuous lighting when the flicker generation acknowledge switch on the display panel 4 is pressed at time t2.

At the time point t3 when the alarm factor is restored, the PLC 42
, The indicator lamp is turned off in the alarm output type Aa.

On the other hand, the return of the alarm factor
When notified from the unit 42, in the alarm output type Ab,
The lighting cycle of the display lamp is generated flicker (time t0 to t
The return flicker has a shorter period than the period (between two), and the alarm sounding period is shorter than the sounding period at the time of occurrence. At time t5, the alarm sound is stopped when the alarm sound stop switch is pressed again, and at time t6, when the return confirmation switch is pressed, the display lamp is turned off.

The flicker control of the display lamp and the alarm sound buzzer sounding control in the alarm output are performed by the data input / output units 321 to 32n which are the slave stations. When a plurality of display data are flickered by the data input / output units 321 to 32n, a plurality of data input / output units 32 serving as slave stations are used.
Unless the flicker cycle or the alarm sounding cycle is synchronized between 1 and 32n by using any method, the cycle will be disturbed.

The present invention has been made in view of such problems, and has a data communication system and a data communication system capable of preventing occurrence of a shift in data communication between data input / output units and a shift such as a flicker cycle. It is intended to provide an input / output unit.

Further, the present invention makes it possible to reliably avoid collision of data frames with a simple configuration even if the connection between the control device and the plurality of data input / output units is a connection of a multidrop type. And a data input / output unit.

[0035]

In this section, for ease of understanding, description will be made with reference numerals in the accompanying drawings. Therefore, the contents described in this section should not be construed as being limited to those given the reference numerals.

The data communication system of the present invention comprises a plurality of data input / output units 421 to 4
In a data communication system in which 2n and 431 to 43n are connected in a multi-drop format, when a data frame is transmitted from each of the plurality of data input / output units to the control device, 1 is transmitted from the control device.
The plurality of data input / output units sequentially transmit data frames with a certain time difference in response to a transmission request command (see step S41 and FIG. 13 in FIG. 12). Invention).

According to the present invention, a plurality of data input / output units sequentially transmit data frames with a fixed time difference in response to one transmission request command sent from the control device. Data frame collision can be avoided even with a connection in the drop format.

In this case, by setting the transmission request command to include a command for designating a transmission time difference between a plurality of data input / output units, for example, the time difference can be set according to the processing capacity of the control device. And the flexibility corresponding to the system is increased (the invention according to claim 2).

Further, the data communication system of the present invention comprises:
A plurality of data input / output units 4
In a data communication system in which 21-42n and 431-43n are connected in a multi-drop format, when transmitting a data frame from each of the plurality of data input / output units to the control device, the plurality of data A different offset value (see FIG. 13, for example, a natural number such as 1, 2, 3,...) Is sequentially assigned to each of the input / output units. A transmission interval time (Ti) obtained by adding a margin time to the transmission time of the data frame, and a transmission reference time (Tr) obtained by multiplying the transmission interval time by the number of the data input / output units. Next, when a transmission request command is simultaneously sent from the control device to each of the plurality of data input / output units, the plurality of data input / output units are transmitted. The power unit sequentially transmits each data frame to the control device with a time difference (transmission interval time × offset value) obtained by multiplying the transmission interval time by the offset value for each data input / output unit. (The invention according to claim 3).

According to the present invention, a plurality of data input / output units sequentially transmit data frames with a fixed time difference (transmission interval time × each offset value) in response to a transmission request command simultaneously notified from the control device. As a result, collision of data frames can be avoided even in the case of multi-drop connection.

In this case, an address is set in advance for each of the plurality of data input / output units, and when transmitting a data frame from the control device to the plurality of data input / output units, the set address is set. A data frame can be transmitted to each of the plurality of data input / output units at fixed time intervals in the order of addresses (the invention according to claim 4).

Further, in the invention according to the fourth aspect, when the control device urgently transmits a data frame to a specific data input / output unit, the data frame transmitted at the predetermined time interval and the data frame transmitted at a constant time interval are transmitted. In the meantime, the data frame to be transmitted urgently is interrupted and transmitted, so that the data to be transmitted urgently can be transmitted in a timely manner without a time delay (claim 5).

Further, in the invention according to any one of claims 1 to 3, when the control device attempts to periodically repeat transmission of data frames to the plurality of data input / output units due to the time difference. At regular intervals, a data frame having a synchronization command is simultaneously transmitted to each data input / output unit, and each of the plurality of data input / output units receiving the data frame has a data frame having the synchronization command. By resetting the reception time as a reference time and restarting the transmission due to the time difference, it is possible to prevent the synchronization deviation from occurring (the invention according to claim 6).

Further, in the invention according to any one of claims 1 to 6, a specific periodic signal supplied from the data input / output unit to at least two of the data input / output units. When the warning means for generating a warning corresponding to the above is connected, the control device simultaneously determines the generation time point of the specific periodic signal with respect to the at least two data input / output units at regular time intervals. By transmitting a data frame having a synchronizing command as a preset signal for synchronizing, it is possible to prevent the synchronizing of the period of the warning generated from the warning means beforehand (the invention according to claim 7).

In the invention according to claim 7,
The cycle of the specific periodic signal supplied from the data input / output unit to the warning unit is set from the control device to the data input / output unit when the system of the data communication system starts operating or when the system is reset. By doing so, the processing load on the control device during the operation of the system is greatly reduced (the invention according to claim 8).

In the invention according to any one of claims 1 to 6, the control device generates at least a signal for controlling opening / closing of a floodgate of the dam, and the data input / output unit includes the signal for controlling the opening / closing of the dam. The data communication system can be operated as a dam control system by connecting a console for operating the opening and closing of the floodgate and / or a display panel for displaying the state of the dam (claim 9). .

In the invention according to any one of the first to ninth aspects, the control device may include a programmable controller (the invention according to the tenth aspect).

Further, the data input / output unit of the present invention is connected to a control device in a multi-drop format and transmits / receives data frames to / from the control device. When having a function, the specifications of the plurality of functions are respectively set from the control device to the data input / output unit when the operation of the data input / output unit is started. invention).

According to the present invention, the versatility of the data input / output unit becomes extremely high.

[0050]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a configuration of a dam control system 40 to which the data communication system of the present embodiment is applied.

The dam control system 40 basically includes a control device 55 for controlling the opening / closing of a floodgate (gate) of the dam and observing a water level of the dam, and a control device for controlling the control device 55. PLC device 45 and this PL
Each of the plurality of (n) data input units 421 to 42n and data output units 431 to 43n connected to the C device 45.

The data input units 421 to 421
42n and / or data output units 431-4
3n, the data input / output units 421 to 42
n, 431 to 43n.

The console 2 and the display panel 4 as external devices are connected to the data input units 421 to 42n and the data output units 431 to 43n. Switches and the like for opening and closing a predetermined amount of the floodgate of the dam are arranged on the console 2.
The display panel 4 has a CRT for displaying the current state of the dam on a video.
A monitor and the like are provided. On a CRT monitor or the like, the surrounding situation including the dam is displayed as an image, and the water level of the dam is displayed in characters.

Further, the console 2 and the display panel 4 have the structure shown in FIG.
7 and FIG. 18, a display lamp as a warning means, a speaker for generating an alarm sound, a stop switch for the generated alarm sound, a generation confirmation switch (generation switch) for confirming the flicker display, , A return confirmation switch (return switch) and the like are appropriately arranged. In FIG. 1, the data input unit 4 is complicated.
Although the console 2 is connected only to the data output unit 431 and the data output unit 431, and the display panel 4 is connected only to the data input unit 422 and the data output unit 432, in practice, all data The console 2 and the display panel 4 can be connected to the input / output units 421 to 42n and 431 to 43n.

The communication I / F unit 44 and the PLC unit 41 are electrically connected to each other by being mounted on a motherboard (not shown). A plurality of data input units 421 to 42n are connected to the communication I / F unit 44 via a signal line (communication line) Ls1 in a multi-drop format.

A plurality of data output units 4 are connected to the communication I / F unit 44 via a signal line (communication line) Ls2.
31 to 43n are connected in a multi-drop format.

In this case, the data input units 421 to 4
2n, a data frame (a group of a plurality of data) is transmitted to the communication I / F unit 44, and a data frame is transmitted from the communication I / F unit 44 to the data output units 431 to 43n. Is done.

For communication between the communication I / F unit 44 and the data input / output units 421 to 42n, 431 to 43n, a general-purpose communication interface RS-232C or RS-485 is used.

In this embodiment, the data input units 421-42n and the data output units 431-43
n are connected by multi-drop connection with different signal lines Ls1 and Ls2, respectively.
4 and each data input / output unit 421-42n, 431-
43n to improve the data transfer speed.
A plurality of data input units 421 to 42 are connected to the same signal line.
n and a plurality of data output units 431 to 43n may be connected.

Each of the data input / output units 421 to 4
In 2n and 431 to 43n, different unit addresses for identifying the unit are set.
The setting of the unit address is performed using dip switches mounted on the data input / output units 421 to 42n and 431 to 43n.

FIG. 2 shows a more detailed configuration of the PLC device 45.

The PLC device 45 is detachably mounted on a motherboard (not shown), and
1, a CPU (central processing unit) unit (control unit) 52, a power supply unit 53, an I / O
PLC composed of unit (input / output unit) 54
It includes a unit 41 and a communication I / F unit 44.

The I / O unit 54 controls the above-mentioned control equipment 55 other than the display panel 4 and the console 2 connected to the data input / output units 421 to 42n and 431 to 43n, for example, a dam gate of a dam. Actuators such as cylinders and motors, telephones, dams and CCTV (closed circuit television) cameras for photographing around the dams, and the like are attached.

FIG. 3 shows a hardware configuration of the communication I / F unit 44. The communication I / F unit 44
A central control unit 62 having a computer function and controlling the entire communication I / F unit 44; and data input / output units 421 to 42n, 43
A data transmission / reception unit 65 composed of an LSI (Large Scale Integrated Circuit) for transmitting data of 1 to 43n is connected.

A program code section 6 composed of a flash memory (ROM) connected to the bus 61
3 stores a control program and an application program for the communication I / F unit 44.

Further, a customized parameter section 64 which is a storage section of a customized parameter constituted by a flash memory (ROM) connected to the bus 61.
The data input / output units 421 to 421 connected to the communication I / F unit 44 in a multi-drop format
Various operation parameters for setting to 42n and 431 to 43n are stored. When the data input / output units 421 to 42n and 431 to 43n have a plurality of functions, for example, the various operation parameters are data for determining specifications such as operation ranges of the plurality of functions.

These various operation parameters are sent to the data input / output units 421 to 42n and 431 to 43n via signal lines Ls1 and Ls2 when the power is turned on. The setting of the customized parameters is performed by downloading the customized parameters suitable for the dam control system 40 from the PLC unit 41 to the communication I / F unit 44.

The dam control system 4 of the present embodiment
0, the communication I / F unit 44 also directly displays the display panel 4
A data output unit 67 and a data input unit 66 are mounted so that the console 2 and the console 2 can be connected.

FIG. 4 shows an example of the hardware configuration of the data input unit 421. The remaining data input units 422 to 42n have the same configuration.

The data input unit 421 has a bus 71, and a central control unit 72 having a computer function and controlling the entire data input unit 421.
And a data transmission / reception unit 74 composed of an LSI (large-scale integrated circuit) for transmitting / receiving a data frame to / from the communication I / F unit 44.

A program code section 7 composed of a flash memory (ROM) connected to the bus 71
3 stores a program of the data input unit 421.

Further, a data input unit (channel 1) 751 to a data input unit (channel 4) 754 are connected to the bus 71, and switch information and the like can be input from the console 2 or the like.

In the present embodiment, each of the data input sections 751 to 754 can handle 16-bit input information (a 4-digit BCD code if a numerical value).

The contents of the customized parameters set in the data input units 421 to 42n from the customized parameter section 64 include a double collation time interval for preventing chattering at the time of data input, and the type of input data (bit string, BCD type numerical value, alarm output control switch, etc.) and the number of digits of numerical data.

Each data input unit 421 performs data input processing using the customized parameters and transmits input data from an external device such as the console 2 according to a communication procedure described in a communication method described later. / F unit 44.

FIG. 5 shows an example of the hardware configuration of the data output unit 431. The remaining data output units 432 to 43n have the same configuration as data output unit 431.

The data output unit 431 has a bus 81, and a central control unit 82 having a computer function and controlling the entire data output unit 431 is provided on the bus 81.
And a data transmission / reception unit 84 composed of an LSI (Large Scale Integrated Circuit) for transmitting data with the communication I / F unit 44.

A program code section 8 composed of a flash memory (ROM) connected to the bus 81
3 stores a control program application program of the data output unit 431.

Further, a data output unit (channel 1) 851 to a data output unit (channel 4) 854 are connected to the bus 81, so that data can be output to the display panel 4 or the like.

In the present embodiment, each of the data output units 851 to 854 can handle 16-bit output information (a 4-digit BCD code if it is a numerical value).

The bus 81 has a data input unit 86 (8
Is connected, and data from the console 2 or the like can be input.

The customized parameters for each channel set in the data output units 431 to 43n from the customized parameter section 64 include display lamps for each of the alarm output types Aa and Ab described with reference to FIGS. Flicker cycle, alarm output type Aa, alarm sound cycle for each Ab, type of output data (bit string, BC
(D-type numeric value, time, etc.), the number of digits of numeric data, the presence or absence of minus display, and the like.

The display lamps and alarm sounds are different from each other.
Alternatively, based on the same specific periodic signal, flicker periodically occurs or the sound is periodically blown.

The data output unit 431 performs data output processing with reference to the customized parameters, and according to a communication procedure described in a data communication method described later, outputs data received from the communication I / F unit 44 as a warning. The information is output to a display panel 4 having a display lamp, a speaker, and the like as a warning output device that also functions as a means.

Next, the communication I / F constituting the PLC device 45
Unit 44 and data input / output units 421 to 42n,
A data communication method with 431 to 43n will be described.

In this embodiment, the normal operation mode for controlling the actual dam and the data input / output units 421 to 42n and 431 to 43n are set prior to the normal operation mode.
There are two types of communication modes: a configuration mode for performing initial settings and the like for adapting to the dam control system 40.

More specifically, in the configuration mode, the customized parameters are transmitted from the customized parameter section 64 of the communication I / F unit 44 to each of the data input / output units 421 to 42n and 431 at the initial stage such as when the system is turned on. To 43n,
Each data input / output unit 421-42n, 431-43
n is a mode used to set specifications that define the function of n.

In the normal operation mode, the transmission of the customized parameters from the customized parameter section 64 to the data input / output units 421 to 42n and 431 to 43n is completed, and the console 2 and the display panel, which are actually external devices, are completed. 4
This mode is used when inputting and outputting data to and the like.

FIG. 6 shows a format of a data frame Fcm which is a communication frame used in the configuration mode. The format of this data frame Fcm uses the transmission mode specified by JIS,
By performing binary data communication, the number of transmission data is reduced.

In the data frame Fcm, the BCC following the end-of-text ETX, which is 1-byte data in hexadecimal notation and is set to "03H (1 byte)", is a horizontal parity check and employs odd parity.

A header (frame header) HEAD following the text start STX set to “02H (1 byte)”
Is header information for identifying the contents of the data frame Fcm, and the information part INFO is data contents other than the header part HEAD.

The length of the information section INFO that can be transmitted in one data frame Fcm is 2029 bytes at the maximum. DLE (data link escape) added as “10H (1 byte)” added in the transparent mode is excluded. ｝.

FIG. 7 shows the data frame Fcm in FIG.
The detailed contents of the header part HEAD are shown.

The command CMD of the first byte is used for identifying the contents of the data frame Fcm.

The main data frames Fcm transmitted by the communication I / F unit 44 include a system start frame, a system stop frame, a connection status request frame, a transmission time difference setting frame upon connection status request, and a customized parameter setting frame. .

On the other hand, the data input / output units 421 to 42
n, the main data frame Fc transmitted by 431 to 43n
m includes a connection information request answer frame. The contents of these data frames Fcm are identified by the command CMD.

The data type DKIND of the next 1 byte is:
Indicates the type of the data frame Fcm. If DKIND = 0, the frame relates to the data input units 421 to 42n. If DKIND = 1, the data output unit 431 to 431
If DKIND = FFH, the frame does not have a distinction between the data input / output units 421 to 42n and 431 to 43n.

The one-byte continuation flag CONT indicates whether or not the data frame Fcm is a divided frame. If CONT = 0, it indicates that the divided frame is continued, and if CONT = FFH, it indicates the end which is a data frame delimiter.

Serial number SEQ of 2-byte continuation frame
NO indicates the serial number of the divided frame FL.
It takes a value of 65535.

The data length DLEN of 2 bytes corresponds to the information section IN.
Indicates the data length of the FO (see FIG. 6). The 1-byte address ADDR is stored in each of the data input / output units 421 to 42n,
4 shows addresses 431 to 43n.

When the communication I / F unit 44 simultaneously transmits the data frame Fcm to all the data input / output units 421 to 42n and 431 to 43n, ADDR = FFH is used as a global address.

The 8-byte parameter PARAM is a parameter added for each command CMD of the data frame Fcm.

FIG. 8 shows an example of a communication procedure in the configuration mode.

First, when power is turned on or when the PLC device 4
When the customized parameter is downloaded from Step 5 to the customized parameter section 64 of the communication I / F unit 44, the communication I / F unit 44 executes the processing in step S1.
, A system stop frame (system stop data frame) is transmitted to each of the data input / output units 421 to 42n and 431 to 43n using a global address.

Each of the data input / output units 421 to 42n and 431 to 43n that have received the system stop frame initializes the inside of the unit.

Next, in step S2, the communication I / F unit 44 transmits, using the global address, a transmission time difference setting frame, which is a command for designating a transmission time difference at the time of connection status request, to each of the data input / output units 421 to 42n,
431 to 43n.

FIG. 9 shows the contents of the information section INFO of the transmission time difference frame Fcmd.

For calculating the transmission time difference represented by 2 bytes of each unit address shown in FIG. 9, the communication I / F unit 44 uses the data input / output units 421 to 42n,
By referring to the customized parameters 431 to 43n, the number of units to be connected and their addresses can be known, and the operation is performed based on the information.

The data input / output units 421 to 42
The transmission time difference between n and 431 to 43n is “connection state request answer frame transmission time + 5 ms extra time”.

Next, in step S3, the communication I / F
Unit 44 sends a connection status request frame.

Each of the data input / output units 421 to 42n,
Upon receiving the connection status request frame, 431 to 43n use the transmission time difference (see FIG. 9) of the unit address stored in the transmission time difference setting frame Fcmd at the time of the connection status request received in step S2 before that. If the transmission time difference has elapsed after the reception of the connection status request frame, in steps S4 (1) to S4 (n), the connection status request answer frame (address 1) to the connection status answer frame (address n) are respectively set. Communication I
/ F unit 44. By performing frame transmission using the time difference in this manner, the signal lines Ls1,
Even if Ls2 is a multi-drop connection type, data frame collision is avoided.

The communication I / F unit 44 sequentially receives the connection status request answer frames transmitted from the data input / output units 421 to 42n and 431 to 43n.

The connection status request answer frame stores the addresses of the data input / output units 421 to 42n and 431 to 43n that have transmitted the connection status request answer frame. Input / output units 421 to 42n,
431 to 43n can be recognized.

Therefore, the data input / output unit 4 which should be connected in the setting by the customized parameter
21-42n and 431-43n can recognize connection information indicating that they are not actually connected, for example, from the lack of a connection status answer frame.

Next, the communication I / F unit 44 includes the data input / output units 421 to 42n, 4
From step S5, the setting information frames including the customized parameters of the data input / output units 421 to 42n and 431 to 43n are sequentially transmitted to 31 to 43n.

The information section INF of this setting information frame
O includes data input / output units 421 to 42n and 431
The transmission reference time and the transmission offset time for performing the time difference transmission in the normal operation mode, which will be described later, are stored in addition to the customized parameters that define the specifications of the functions of .about.43n.

The transmission reference time and the transmission offset time will be described in detail in the communication method in the normal operation mode described later.

The data input / output units 421 to 42n and 431 to 43n that have received the setting information frame are converted from the data input / output units 421 to 42n, 431 to 43n from the addresses (see ADDR in FIG. 7) in the setting information frame.
When it is determined that the frame is the setting information frame of n, the contents are referred to and the customized parameters and the like are stored in the RAM area in the unit (random access memory mounted in each of the data input / output units 421 to 42n and 431 to 43n). save.

The data input / output units 421 to 42
If the setting information frame has been normally taken in, the n, 431 to 43n return an acknowledgment (ACK) to the communication I / F unit 44 in step S6, for example.

If no acknowledgment is returned from data input / output units 421 to 42n and 431 to 43n, communication I / F unit 44 attempts to retransmit the setting information frame a specified number of times.

The communication system described in the normal operation mode described later includes an acknowledgment (ACK) and a negative acknowledgment (NA).
There is no protocol such as K).

The contents of the setting information frame determine the functions of the data input / output units 421 to 42n and 431 to 43n. The system cannot operate unless the data is correctly received. Is adopted.

Therefore, for example, when a negative acknowledgment (NAK) as shown in step S8 is returned in response to the transmission of the setting information frame (address 2) in step S7, the setting information is again sent in step S9. Transmit the frame (address 2).

If an acknowledgment (ACK) is returned in step S10, the transmission of the setting information frame (address n) in step S11 and the return of the acknowledgment (ACK) in step S12 are successively performed. Is repeated.

Finally, in step S13, the communication I
/ F unit 44 includes data input / output units 421 to 421
When the transmission of the setting information frame to 42n, 431 to 43n is completed, a system start frame, which is a transmission request command, is simultaneously transmitted to each data input / output unit 421 to 42n, 431 to 43n using a global address. Then, the mode shifts to the normal operation mode.

Next, the transfer of data frames between the data input / output units 421 to 42n and 431 to 43n in the normal operation mode will be described.

FIG. 10 shows the format of a communication frame (data frame) Fom used in the normal operation mode. The format of the communication frame Fom also uses the transparent mode defined by JIS similarly to the configuration mode, and reduces the number of transmission data by performing binary data communication.

In the data frame Fom, the BCC following the text end ETX of “03H (1 byte)” is a horizontal parity check, and employs odd parity.

[0130] Text start S of "02H (1 byte)"
A one-byte command CMD following TX is used to identify the frame contents. In the normal operation mode, the main data frames Fom transmitted by the communication I / F unit 44 include an output data frame and a synchronization command frame. Data input / output units 421-4
The main frames transmitted by 2n and 431 to 43n include input data frames. The types of these frames are identified by the command CMD.

ADDR of 1 byte indicates an address of the data input / output units 421 to 42n and 431 to 43n.
When the communication I / F unit 44 simultaneously transmits the data frames Fom to all the data input / output units 421 to 42n and 431 to 43n, ADDR = FFH is used as a global address. 2-byte D
LEN indicates the length of the information section.

The communication I / F unit 44 converts output data frames in the data frame Fom format into data input / output units 421 to 42n connected to the external device in order to display data or the like on an external device such as the display panel 4. 431-
43n.

In the information section INFO of the output data frame, in addition to the data actually output to the external device, the presence / absence of flicker of the display lamp, the presence / absence of the alarm sound, and the alarm output types Aa, Ab (FIG. 17) And FIG. 18)
Is stored.

Data input / output units 421 to 42n, 4
When the output data frame storing its own address is received normally, the consoles 31 to 43n use the contents of the information section INFO and the customized parameters in the data frame to operate the console 2 and the display panel 4 etc. Output data to external devices.

At this time, if start of lamp flicker or start of alarm sound is instructed in the output data frame,
The flicker of the display lamp on the console 2 or the display panel 4 and the alarm sounding are started.

Thereafter, the data input / output units 421 to 4
2n, 431 to 43n normally receive the output data frame storing the stop of the lamp flicker and the stop of the alarm sound from the communication I / F unit 44.
Alternatively, the flicker of the display lamp on the display panel 4 or the alarm sounding is stopped.

On the other hand, data input / output units 421 to 42
n, 431 to 43n transmit data input from an external device such as the console 2 or the display panel 4 to the communication I / F unit 44.
, An input data frame in the data frame Fom format is used. In this case, the unit address ADDR contains the data input / output unit 421 to 421 of the transmission source.
42n and 431 to 43n are stored. The information section INFO stores input data from which chattering and the like have been removed in accordance with the customized parameters.

FIG. 11 shows a case where the communication I / F unit 44 includes the data input / output units 421 to 42n and 431 to 43n.
3 shows a communication procedure when transmitting an output data frame in the data frame Fom format.

In step S21 (the same step as step 13 in FIG. 8), the communication I / F unit 44 enters the normal operation mode after transmitting the system start frame.

[0140] The communication I / F unit 44 executes step S1.
21 and thereafter, the output data frames are transmitted in ascending order of the unit addresses at regular time intervals tc (tc = 1 second) (steps S122 to S12n, step S3).
1). Thereby, each data input / output unit 421-4
2n, 431 to 43n can always receive the latest output data.

However, if an event that requires changing the displayed data (such as a change in display data value or the occurrence / return of an alarm event relating to information) occurs in the PLC device 45, as shown in step S122a. The output data frame (address 4) whose display has been changed between the output data frame (address 2) and the output data frame (address 3) to be transmitted in the ascending order is transmitted. The display can be updated instantaneously due to the change.

In the data input / output units 421 to 42n and 431 to 43n according to the present embodiment,
In general, a hardware timer circuit is used to control flickering of a lamp on a console 2 or a display panel 4 as an external device or sounding of an alarm. However, since the timer circuit is independent for each of the data input / output units 421 to 42n and 431 to 43n, the cycle of flicker and alarm sound is not synchronized between the data input / output units 421 to 42n and 431 to 43n. , There is a possibility of synchronization loss.

In order to avoid the possibility of the occurrence of the synchronization shift, the communication I / F unit 44 has a predetermined period, for example,
Normally, each of the data input / output units 421 to 42n, 4
31 to 43n transmit the synchronization command frame all at once using the global address, as shown in step S124a, with the least common multiple of the cycle interval of lamp flicker and alarm sounding.

Each of the data input / output units 421 to 42n,
Upon receipt of this synchronization command frame, 431 to 43n store an internal control counter (located on RAM) used for lamp flicker and alarm sounding in this synchronization command frame (data having a synchronization command). By presetting the reception time of a frame as a reference time, synchronization can be achieved.

Here, the preset processing means that, when the resolution of the timer circuit is 10 msec and the lamp is to be turned on and off every 100 ms, the internal counter usually rotates at a value of 0 to 9 and the internal counter rotates. The lamp will be turned on or off when the counter reaches zero. In this case, the counter is set to 0 by presetting, and flicker is restarted from the off state.

FIG. 12 shows data input / output units 421-421.
42n and 431 to 43n show communication procedures when transmitting an input data frame in which data is input from the console 2 or the like to the communication I / F unit 44. Also in this case, the normal operation mode is set after the communication I / F unit 44 transmits the system start frame with the global address in step S41.

In the normal operation mode, the transmission reference time and the transmission offset time in the setting information frame received after step S5 in the configuration mode (communication procedure in FIG. 8) are used to set the global address in step S41. The data input / output units 421 to 42n and 431 to 43n simultaneously receive the system start frame (also used as the synchronization command frame) and the synchronization command frame in step S42 at the timing of the time chart shown in FIG. Steps S241 to S24n and steps S341 to S3, respectively
4n, the transmission of the input data frames from address 1 to address n is repeated.

The time chart of FIG. 13 will be described in detail. At time t10, the data input / output units 421 to 42n receive the synchronization command frame of step S41 or step S42 all at once by specifying a global address.

Here, a time obtained by adding a margin time (5 ms in this embodiment) to the transmission time of the input data frame in step S241 and the like is defined as a transmission interval time Ti.

The communication unit 44 is set at the transmission interval time Ti.
Is multiplied by the number of data input / output units 421 to 42n and 431 to 43n connected in a multidrop format to a transmission reference time Tr.

At this time, at the first timing after receiving the synchronization command, the data input / output units 421, 431
When the offset time of the input data frame (address 1) output from the device is set to To1, the offset time To1 is set to To1 = Ti × 1. Next, the offset time To2 of the input data frame (address 2) output at the second timing is set to To2 = Ti × 2, and the offset time To2 of the input data frame (address n) output at the last n-th timing is set. Offset time Ton is T
Let on = Ti × n.

By transmitting the input frame based on the time difference, the communication I / F unit 44 can prevent the frame collision and the data input / output units 421 to 42
n, 431 to 43n can be received.

However, similarly to the lamp flicker and alarm sound in the output data, each data input / output unit 421
Due to the synchronization deviation of the timer circuits of と と も に 42n and 431４３43n, there is a possibility that the transmission cycle is distorted with the passage of time and data collision occurs. In order to avoid this problem, the communication I / F unit 44 transmits a synchronization command frame similar to the synchronization command frame described in the flicker control at a fixed period as shown in step S42. Each data input / output unit 421-42
n, 431 to 43n, upon receiving the synchronization command frame, presets the transmission reference time Tr, and sets the data input / output units 421 to 421 having the smallest address.
The input data frame is transmitted again from 42n and 431 to 43n.

As described above, according to the above-described embodiment, a plurality of data input / output units 421 to 42
n, 431 to 43n can be multi-drop connected, and data is exchanged between the communication I / F unit 44 as a master station and the plurality of data input / output units 421 to 42n, 431 to 43n.

In this case, the data input / output units 421 to 421
42n and 431 to 43n transmit data to the communication I / F unit 44 with a time difference, so that collision of transmission data does not occur.

On the other hand, the communication I / F unit 44 periodically sends a synchronization command for adjusting the time difference of data transmission and the synchronization of the flicker cycle to the data input / output unit 42.
Since the data is transmitted to the data input / output units 1 to 42n and 431 to 43n, it is possible to prevent a time difference in data transmission between the data input / output units 421 to 43n and a synchronization shift in the flicker cycle.

As described above, by the simple communication procedure, it is possible to avoid the occurrence of collision of transmission data, and to prevent the time difference of data transmission and the synchronization of flicker cycle.

The data input / output units 421 to 42
Various functions related to data display, switch input, and the like (for example, a flicker function of a display lamp according to an alarm output type) are installed in advance in n and 431 to 43n, and customized parameters for adapting to an actual system are provided. It is possible to set the communication I / F
From unit 44 to dam control system 4 which is an actual system
By transmitting the customized parameter for matching 0, the data input / output units 421 to 42n,
Since the 431 to 43n perform operations related to data display and switch input suitable for the dam control system 40, the PLC unit 41 and the communication I / F unit 44 do not need to store a complicated program related to data display. Further, it is possible to implement functions related to data display and switch input / output suitable for the actual dam control system 40 without adding or changing a software program.

In the present embodiment, the PLC device 45 is connected to the data input / output units 421 to 42n and 431 to 43n via the communication I / F unit 44. Data input / output units 421 to 42
n, 431 to 43n can be connected.

In such a configuration, the personal computer is provided with the communication function of the communication I / F unit 44 described in this embodiment, so that a data communication system (data input / output system) can be easily realized. It is also possible to build.

[0161]

As described above, according to the present invention, a plurality of data input / output units sequentially transmit data frames with a fixed time difference in response to one transmission request command sent from the control device. Therefore, the effect of reliably avoiding collision of data frames with a simple configuration can be achieved even in the case of connection in a multi-drop format.

Further, the control device periodically transmits a synchronization command for adjusting the time difference of data communication and the synchronization of the flicker cycle to the data input / output unit. Can be prevented by a simple communication procedure.

The data input / output unit has various functions related to data communication and switch input, for example, a flicker function of a display lamp according to an alarm output type.
Pre-installed and customized parameters for adapting to the actual system can be set, and by sending the customized parameters for adapting to the actual system from the controller, the data input / output unit displays data suitable for the system. By determining the operating specifications for the switch input and the switch input, the control device, for example, the PL
The C section and communication I / F unit do not require complicated programs related to data display, and implement functions related to data display and switch input suitable for the actual system without adding or changing software programs. It is possible to do.

Further, according to the present invention, it is possible to prevent the occurrence of a shift in data communication between data input / output units and a shift such as a flicker cycle.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a dam control system to which a data communication system according to an embodiment is applied.

FIG. 2 is a block diagram showing a configuration example of a PLC device in the dam control system of FIG. 1;

FIG. 3 is a block diagram showing a configuration example of a communication I / F unit in the dam control system shown in FIG. 1;

FIG. 4 is a block diagram showing a configuration example of a data input unit in the dam control system of FIG. 1;

FIG. 5 is a block diagram showing a configuration example of a data output unit in the dam control system of FIG. 1;

FIG. 6 is a diagram illustrating a frame configuration in a configuration mode in the dam control system of FIG. 1;

7 is a diagram illustrating a configuration of a header in a frame in a configuration mode in the example of FIG. 6;

FIG. 8 is a diagram showing an example of a communication procedure in a configuration mode in the dam control system of FIG. 1;

9 is a diagram illustrating an example of an information portion of a transmission time difference frame at the time of a connection status request in the dam control system in the example of FIG. 1;

FIG. 10 is a diagram showing a frame configuration in a normal operation mode in the dam control system of FIG. 1;

11 is a diagram showing an example of a communication procedure in a normal operation mode in the dam control system in the example of FIG. 1;

FIG. 12 is a diagram showing another example of a communication procedure in the normal operation mode in the dam control system of FIG. 1;

FIG. 13 is a time chart for explaining a transmission reference time and a transmission offset time in the dam control system of FIG. 1;

FIG. 14 is a block diagram showing a configuration of a data communication system according to the related art.

FIG. 15 is a diagram showing the contents of communication data according to the related art.

FIG. 16 is a block diagram showing a configuration of another example of the data communication system according to the related art.

FIG. 17 is a time chart showing an example of an alarm output type.

FIG. 18 is a time chart showing another example of the alarm output type.

[Explanation of symbols]

2 console 4 display panel 40 dam control system 41 PLC unit 44 communication I / F unit 45 PLC device 51, 61, 71, 81 bus 52 CPU unit 53 power supply unit 54 I / O Unit 55: Control devices 62, 72, 8
2 Central control section 63, 73 Program code section 64 Customized parameter section 65, 74, 84 Data transmission / reception section 66, 86, 751-754 Data input section 67, 851-854 Data output section 421-42n ... Data input units 431 to 43n ... Data output units Aa, Ab ... Alarm output type Fcm ... Data frame (in configuration mode) Fom ... Data frame (in normal operation mode) Ls1, Ls2 ... Signal lines (communication lines)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Eiji Ikari 5-1-1, Shimorenjaku, Mitaka-shi, Tokyo Japan Radio Co., Ltd. (72) Hiroyasu Shibata 2- 10-19 Tori, Ueda-shi, Nagano Ueda Nippon Radio Co., Ltd. (72) Inventor Takehiro Shimizu 2--10-19 Tori, Ueda-shi, Nagano Ueda Nippon Radio Co., Ltd. (72) Inventor Kazuto Ogawa 2--10, Ueda-shi, Nagano, Japan No. 19 Ueda Nippon Radio Co., Ltd. (72) Inventor Shuichi Takahashi 2-10-19, Ueda City, Nagano Pref. Ueda Nippon Radio Co., Ltd. JJ38 JJ55 5K032 AA05 BA08 CA13 CB06 DA01

Claims (11)

[Claims] 1. A data communication system in which a plurality of data input / output units are connected to a control device in a multi-drop format, wherein each of the plurality of data input / output units transmits a data frame to the control device. In this case, the data communication system is characterized in that the plurality of data input / output units sequentially transmit data frames with a certain time difference in response to one transmission request command sent from the control device. 2. The data communication system according to claim 1, wherein said transmission request command includes a command for designating a transmission time difference between said plurality of data input / output units. . 3. A data communication system in which a plurality of data input / output units are connected to a control device in a multi-drop format, wherein each of the plurality of data input / output units transmits a data frame to the control device. At this time, in advance, different offset values are sequentially assigned to each of the plurality of data input / output units. Next, the transmission of the data frame from the control device to each of the plurality of data input / output units is performed. A transmission interval time obtained by adding a margin time to a transmission time and a transmission reference time obtained by multiplying the transmission interval time by the number of the data input / output units are transmitted. When notifying each of the output units at the same time, the plurality of data input / output units Data communication system, characterized in that sequentially transmits over data the offset value each data frame with a time difference obtained by multiplying the per output unit to the control device. 4. The data communication system according to claim 1, wherein an address is set in advance for each of said plurality of data input / output units, and said plurality of data input / output units are transmitted from said control device. When transmitting a data frame to a unit, a data frame is transmitted for each of the plurality of data input / output units at fixed time intervals in the order of the set addresses. 5. The data communication system according to claim 4, wherein, when urgently transmitting a data frame from the control device to a specific data input / output unit, the data frame and the data transmitted at the fixed time interval are transmitted. A data communication system, wherein the data frame to be transmitted urgently is interrupted between frames and transmitted. 6. The data communication system according to claim 1, wherein the control device attempts to periodically repeat transmission of a data frame to the plurality of data input / output units due to the time difference. Then, at regular time intervals, a data frame having a synchronization command is transmitted to each data input / output unit at the same time, and each of the plurality of data input / output units receiving the data frame has the synchronization command. A data communication system, wherein a data frame reception time is preset as a reference time, and transmission based on a time difference is restarted. 7. The data communication system according to claim 1, wherein at least two of the data input / output units are supplied from the data input / output unit. When a warning means for generating a warning corresponding to the periodic signal is connected, the control device generates the specific periodic signal simultaneously with the at least two data input / output units at regular time intervals. A data communication system for transmitting a data frame having a synchronization command as a preset signal for adjusting a time point. 8. The data communication system according to claim 7, wherein the cycle of the specific periodic signal supplied from said data input / output unit to said warning means is set when the system of said data communication system starts operating or when the system is reset. A data communication system, which is sometimes set from the control device to the data input / output unit. 9. The data communication system according to claim 1, wherein the control unit generates at least a signal for controlling opening / closing of a floodgate of the dam, wherein the data input / output unit includes: A data communication system, wherein an operation console for operating the opening and closing of a floodgate of the dam and / or a display panel for displaying a state of the dam are connected. 10. The data communication system according to claim 1, wherein the control device includes a programmable controller. 11. A data input / output unit which is connected to a control device in a multi-drop format and transmits / receives a data frame to / from the control device, wherein the data input / output unit has a plurality of functions. The data input / output unit is set from the control device to the data input / output unit when the operation of the data input / output unit is started.