JPH08298513A - Control communication system - Google Patents

Abstract

PURPOSE: To eliminate work for setting address numbers to respective slave stations and for registering the number of the slave stations in a control communication system provided with a master station and the plural slave stations. CONSTITUTION: At the time of registering the number of the slave stations, eight bit data of a high level is inputted to the input/output register 11 of the master station, and the data are sequentially shifted in accordance with eight shift clocks and are transmitted to the shift registers 221 -224 of the slave stations, for example. Then, data of the shift registers 221 -224 in the slave stations are returned to the input/output register 11 of the master station in accordance with eight shift clocks. The master station grasps the number of the slave stations from a difference between data transmitted to the slave station and data returned from the slave station, thereby specifying the respective slave stations.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention transmits, for example, an on / off control signal from a control controller or the like to an output device such as an air valve or an actuator of a machine tool or a limit switch or various sensors. The present invention relates to a control communication system suitable for transmitting an on / off state signal from an input device to the control controller or the like.

[0002]

2. Description of the Related Art In such a control communication system,
Direct wiring between the control controller and output device, or between the control controller and input device, complicates the wiring configuration, requires more work for wiring, and increases the number of wires, resulting in high cost. Will be.

Therefore, as a control communication system with reduced wiring, as shown in FIG. 14, a master station 31 connected to a control controller 30 and an output device such as an actuator or an input device such as various sensors are connected. is provided with a plurality of the slave station 32 ₁ ~32n, and outputs a control signal on-off transmitted from the master station 31 to an output device via the slave station 32 ₁ ~32n, or on-off from the input device The status signal is taken into the slave stations 32 _{1 to} 32n and the master station 3
There is a configuration in which the data is transmitted to one.

[0004]

However, in such a control communication system, when the system is started up, in order for the master station 31 to be able to identify the plurality of slave stations 32 ₁ to 32 n, an operator However, there is a problem that it is necessary to set an address number for each slave station or register the number of slave stations.

Further, in the conventional system, even if an abnormality occurs in the transmission line due to disconnection or noise, it is difficult to find out the cause of the abnormality.

Further, when the system is started up,
When confirming whether or not the signal is normally transmitted between the master station 31 and the slave stations 32 _{1 to} 32 n installed at a location distant from the master station 31, for example, the slave station is 32 ₁
Up to 32n, an operator who sees the on / off state of input devices such as various sensors, and an operator who checks the state signal of the input device transmitted from the slave stations 32 _{1 to} 32n on the master station 31 side. There is a drawback that it requires a person and the confirmation work is troublesome.

The present invention has been made in view of the above points, and in a control communication system including a master station and a plurality of slave stations, an address number is set for each slave station or the number of registered slave stations is registered. It is an object of the present invention to eliminate the need for a work such as to do so, to make it possible to immediately detect a transmission path abnormality such as a disconnection, and to easily confirm whether or not transmission is normally performed.

[0008]

In order to achieve the above-mentioned object, the present invention is constructed as follows.

That is, according to the present invention of claim 1, a master station and a plurality of slave stations are connected in cascade, and the data of the master station is transferred from the upstream slave station which is the master station side to the downstream slave station. A control communication system for transmitting to a slave station by sequentially shifting, and transmitting the data of the slave station from a slave station on the downstream side to a slave station on the upstream side, and transmitting to the master station by sequentially shifting, When transmitting predetermined data to the plurality of child stations, the parent station specifies each child station based on the data returned from the plurality of child stations.

According to the present invention of claim 2, a master station and a plurality of slave stations are connected in cascade, and the data of the master station is sequentially transferred from the upstream slave station which is the master station side to the downstream slave station. A control communication system that transmits to a slave station by shifting, and transmits data of the slave station from a slave station on the downstream side to a slave station on the upstream side by sequentially shifting to the master station, wherein the master station The station identifies each slave station based on predetermined data transmitted from the plurality of slave stations.

According to a third aspect of the present invention, in the control communication system according to the first or second aspect, the master station determines each slave station by obtaining the number of slave stations.

According to a fourth aspect of the present invention, in the control communication system according to any one of the first to third aspects, at least one slave station of the plurality of slave stations performs a predetermined process on the data transmitted from the master station. Then, the master station detects the abnormality based on whether or not the data subjected to the predetermined processing is returned.

According to a fifth aspect of the present invention, in the control communication system according to the fourth aspect, the at least one slave station is the most downstream slave station.

According to a sixth aspect of the present invention, in the control communication system according to any one of the first to fifth aspects, the slave station displays the data according to the data transmitted from the master station, and the slave station. An input unit to which data from an input device connected to the station is input, and transmits the data from the input unit to the master station, the master station transmitting the data transmitted from the slave station. It will be returned.

According to a seventh aspect of the present invention, in the control communication system according to any one of the first to sixth aspects, the slave station is operated to confirm whether or not data is normally transmitted. And a display unit that displays according to the data transmitted from the master station, and transmits monitoring data according to the operation of the operation unit to the master station, the master station from the slave station. The transmitted monitor data is returned.

According to the present invention of claim 8 in the control communication system according to any one of claims 1 to 7, cascade connection is made to supply power to each slave station from the master station to the most downstream slave station. In addition to the power supply line, the power supply line is directly connected from the most downstream slave station to the master station.

[0017]

According to the present invention of claim 1 or 3, the data of the master station is sequentially shifted from the upstream side to the downstream side and transmitted to the slave station, and the data of the slave station is sequentially streamed from the downstream side to the upstream side. Since the data is shifted and transmitted to the master station, for example, if 8-bit high-level data is shifted bit by bit and transmitted to the slave station and the slave station returns the data, the number of slave stations is eight. If so, 8-bit data will be returned as it is, but if the number of slave stations is less than 8,
Since only data of less than 8 bits will be returned as it is, the number of slave stations can be calculated from the difference between the data transmitted to the slave station and the data returned from the slave station, and the number of slave stations Since the position of the slave station is determined depending on whether or not the slave station is connected, each slave station can be specified, and there is no need to set an address number for each slave station as in the conventional example.

According to the present invention of claim 2 or 3, the data of the master station is sequentially shifted from the upstream side to the downstream side and transmitted to the slave station, and the data of the slave station is sequentially streamed from the downstream side to the upstream side. Since the data is shifted and transmitted to the master station, for example, if each slave station transmits 1-bit high-level data, the master station obtains high-level data of the number of bits corresponding to the number of slave stations. Therefore, the number of slave stations can be calculated, and the position of each slave station is determined by the number of connections from the master station. Therefore, each slave station can be specified. There is no need to set an address number for each slave station.

According to the present invention of claim 4, at least one slave station performs a predetermined process on the data transmitted from the master station and returns the data to the master station, and the master station receives the master station. Since the abnormality is detected based on whether or not the data subjected to the process is returned, when an abnormality occurs in the transmission line due to disconnection or noise between the master station and the at least one slave station, , You will be able to detect it immediately.

According to the present invention of claim 5, since at least one slave station is the most downstream slave station, there is no disconnection or abnormality in the transmission line between the master station and the most downstream slave station. When it occurs, it can be detected immediately.

According to the sixth aspect of the present invention, by confirming that the display unit of the slave station is displayed according to the on / off state of the input device, the slave station and the master station are connected to each other. It is possible to easily confirm whether or not the data is normally transmitted.

According to the present invention of claim 7, when the operation unit of the slave station is operated, the monitor data is transmitted to the master station, and the monitor data is returned from the master station to the display unit of the slave station.
Since the display according to the monitor data is performed, by the operation of the operation unit and the display of the corresponding display unit,
It is possible to easily confirm whether or not the data is normally transmitted between the slave station and the master station.

According to the present invention of claim 8, in the power supply line cascade-connected to supply power to each slave station from the master station to the slave station on the most downstream side, the slave stations on the downstream side are sufficiently connected. Even when a large power supply cannot be supplied, the power can be supplied via a power supply line provided separately from the power supply line.

[0024]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is an overall configuration diagram of a control communication system according to an embodiment of the present invention.

The control communication system of this embodiment comprises a programmable controller 1, a master station 2, and a plurality of (four in this embodiment) slave stations 3 _{1 to} 3 _4.
And the four slave stations 3 _{1 to} 3 ₄ are connected in series via a cable, and the master station 2 side is the upstream side.

In this embodiment, each slave station 3 ₁ except the most downstream slave station (hereinafter also referred to as "end station") 3 ₄
To 3 ₃ are connected with input devices 4 ₁ to 4 ₃ such as various sensors, and the master station 2 controlling the slave stations 3 _{1 to} 3 ₄ is the slave station 3 ₁ to.
The ON / OFF state signals of the input devices 4 ₁ to 4 ₃ transmitted from 3 ₃ are given to the programmable controller 1, and the programmable controller 1 controls a machine tool or the like (not shown) based on the signal. Power is supplied to each of the input devices 4 ₁ to 4 ₃ through the power supply lines of the slave stations 3 ₁ to _{3 3} that are connected in cascade from the master station 1.

The data of the master station 2 is sequentially shifted from the upstream (master station 2) side to the downstream side and transmitted to the slave stations 3 _{1 to} 3 ₄ , and the data of the slave stations 3 _{1 to} 3 ₄ is transferred from the downstream side. The signals are sequentially shifted to the upstream side and transmitted to the master station 2.

In this embodiment, as described above, each slave station 3
_{1 to} 3 ₃ are dedicated to inputs in which only input devices 4 ₁ to 4 ₃ such as various sensors are connected, and in a normal operating state, as will be described later, from input devices 4 ₁ to 4 ₃ Each slave station 3 ₁
The data taken in by ~ 3 ₃ are sequentially shifted and transmitted to the master station 2 side, and the master station 2 gives the data to the programmable controller 1 and also sequentially shifts the data again to make the slave stations 3 ₁ ... 3 is ₄ to repeat the operation of returning to.

[0030] The most downstream slave station 3 _4, the output device such as an input device or actuator is not connected, as described below, in order to detect the abnormality of the transmission path such as disconnection, transmitted from the master station 2 The processed data is inverted and returned to the master station 2.

FIG. 2 is a block diagram showing the configuration of the master station 2 of FIG.

The master station 2 is a control signal terminal 5 connected to a control signal line and a data signal terminal connected to a data signal line for inputting / outputting data between the slave stations 3 _{1 to} 3 _4. 6 and a ground terminal 7.

Further, the master station 2 is connected to the slave station 3 ₁
To 3 to ₄ volume and number registration circuit 8 to register as described later, a data input-output circuit 9 for outputting data data to the input or the programmable controller 1 from the programmable controller 1, the data of the end station 3 ₄ An end station check register 10 for monitoring, an input / output register 11 for holding data, a command for controlling the slave stations 3 _{1 to} 3 ₄ and a control signal composed of a shift clock for sequentially shifting data are generated. A control circuit 12 for controlling transmission, a synchronizing circuit 13 for synchronizing each block, a control signal output circuit 14 for outputting a control signal, and an input / output for inputting / outputting data between the slave stations 3 _{1 to} 3 _4. The output circuit 15 and the abnormality output circuit 35 having a display element or the like for notifying the abnormality of the transmission path are provided.

A maximum of eight slave stations can be connected to the master station 2 of this embodiment, and the input / output register 11 has an 8-bit structure so as to hold 1-bit data of each slave station. The command transmitted from the master station to each slave station is the data transmitted from the master station side to the slave station side, the data transmitted from the slave station side to the master station side, the data of the slave station connected to the slave station. There are four types: output to an output device that is present and input of data of an input device connected to the slave station to the slave station.

FIG. 3 shows slave stations 3 ₁ to ₃ 3 other than the end station 3 _4.
FIG. 3 is a block diagram showing the configuration of FIG.

The slave stations 3 _{1 to} 3 ₃ are connected to the control signal line, the data signal line and the ground line of the master station 2 or the upstream slave stations 3 _{1 to} 3 ₂ , respectively, and control signal terminals 16 u and data signals. In addition to having a working terminal 17u and a ground terminal 18u, each terminal 16d, 17d, 18d is connected to the corresponding line of the slave stations 3 _{2 to} 3 ₄ on the downstream side.

Further, the slave stations 3 _{1 to} 3 ₃ are input latch circuits for latching on / off state signals from the input devices 4 ₁ to 4 ₃ such as various sensors and operation signals of the check switch 27 for confirming the operation to be described later. 20, the upstream and downstream input / output circuits 21u and 21d, 1-bit shift registers 22 _{1 to} 22 ₃ to which data is written or read via the input / output circuits 21u and 21d, and the shift register 22
An output latch circuit 24 for latching the contents of _{1 to} 22 ₃ via the input / output circuit 21d and outputting them to an output device such as the display LED 23 or an actuator, and a control signal from the master station 2 are input to the shift register Two
And a controller 25 for controlling the 2 _{1-22 3,} the shift register 22 ₁ to 22 _3, in conjunction with commands from the controller 25 is made to be able to switch the input and output direction.

[0038] FIG. 4 is a block diagram showing the configuration of the end station 3 _4, portions corresponding to FIG. 3, the same reference characters.

The end station 3 ₄ is not provided with a terminal and an input latch circuit output devices such as an input device or an actuator such as various sensors are connected, the output of the output latch circuit 24 through an inverter 26 upstream It is adapted to be applied to the input / output circuit 21u on the side. Other configurations are similar to those of the other slave stations 3 _{1 to} 3 ₃ .

In the control communication system of this embodiment, when data is transmitted from the master station 2 to the slave stations 3 _{1 to} 3 ₄ , the data in the input / output register 11 of the master station 2 responds to the shift clock of the control signal. 1 bit at a time from the upstream slave station to the downstream end station 3 ₄ in sequence, and conversely, when transmitting data from the slave stations 3 _{1 to} 3 ₄ to the master station 2, each slave station 3 4 _{1 to} 3 ₄ shift registers 22 ₁ to 2
2 ₄ data, and transmit the output register 11 of the master station 2 by sequentially shifted from the downstream side to the upstream side.

FIGS. 5 and 6 are timing charts showing the state of this transmission. FIG. 5 shows the master station 2 to the slave station 3.
Slave station 3 ₁ to 3 ₄ Control signal lines when transmitting data to a _{1-3 4} shows the signal of the data signal lines of the upstream and downstream side, FIG. 6, the master station from the slave station 3 ₁ to 3 ₄ 2 shows the signals of the respective signal lines of the slave stations 3 _{1 to} 3 ₄ when transmitting data to _No. 2.

In the case of transmitting data from the master station 2 to the slave stations 3 _{1 to} 3 ₄ , in response to the shift clock of the control signal of FIG. 5A, the upstream side shown in FIG. Input data is shifted bit by bit and is output to the downstream side as shown in FIG. 5 (C).

When data is transmitted from the slave stations 3 _{1 to} 3 ₄ to the master station 2, in response to the shift clock of the control signal of FIG. 6 (A), the downstream shown in FIG. 6 (B). The input data from the side is shifted bit by bit, as shown in FIG.
As shown in (C), it outputs to the upstream side.

In this embodiment, in order to automate the registration of the numbers of the slave stations 3 _{1 to} 3 ₄ and to eliminate the work of setting the address numbers of the slave stations and the work of registering the numbers as in the conventional example, the following steps are performed. Is configured.

FIG. 7 shows the input / output register 11 of the master station 2 and the slave stations 3 _{1 to} 3 ₄ for explaining the procedure for registering the number of units.
1 is a diagram showing 1-bit shift registers 22 _{1 to} 22 ₄ .

First, when the system is started up, such as when the power is turned on, the master station 2 as shown in FIGS.
“1” is input to each bit of the 8-bit input / output register 11.

Next, in synchronization with the eight shift clocks following the command to transmit the data of the master station 2 to the slave stations 3 _{1 to} 3 ₄ , the 8-bit data of the input / output register 11 is transferred to the upstream side. Are sequentially shifted to the downstream side and are input to the 1-bit shift registers 22 _{1 to} 22 ₄ of the respective slave stations 3 _{1 to} 3 ₄ as shown in FIG.

Next, in synchronization with the eight shift clocks following the command to transmit the data of the slave stations 3 _{1 to} 3 ₄ to the master station 2, the data of the slave stations 3 _{1 to} 3 ₄ are transferred to the downstream side. Are sequentially shifted to the upstream side and are input to the 8-bit input / output register 11 of the master station 2 as shown in FIG.

In this embodiment, four slave stations 3 _{1 to} 3 ₄ are connected to the master station 2 to which a maximum of 8 slave stations can be connected, so that it is shown in FIG. respect as in the 8-bit data for all the high level transmission, from the slave station 3 ₁ to 3 _4, that only 4 bits sent back data the high level as shown in FIG. (D) become.

As shown in FIG. 8, the master station 2 shifts the shift clock shown in FIG. 8A in the high level period of the data shown in FIG. 9B returned from the most upstream slave station 3 ₁ . The number of slave stations 3 _{1 to} 3 ₄ is grasped and registered in the number registration circuit 8, and the end station is arranged on the most downstream side. It recognizes that the eye slave station is the end station 3 ₄ , and thereafter, the data corresponding to this slave station 3 ₄ is given to the end station check register 10, and the data returned from the end station 3 ₄ is always inverted. Monitor whether or not it has been done.

As described above, when the system is started up such as when the power is turned on, predetermined data is transmitted from the master station 2 to the slave station 3.
_{1 to} 3 ₄ , and the master station 2 obtains and registers the number of units based on the data returned from the slave stations 3 _{1 to} 3 ₄ , so that the address number setting work and registration are performed as in the conventional example. No need to set the number of units.

In this embodiment, the predetermined number of data is transmitted from the master station 2 and the number of units is calculated based on the data returned from the slave stations 3 _{1 to} 3 _4. However, as another embodiment of the present invention, For example, when starting up the system, each slave station 3 ₁ ~
Input "1" into the shift registers 22 _{1 to} 22 ₄ of 3 ₄ ,
The data of the slave stations 3 _{1 to} 3 ₄ may be transmitted to the master station 2 in accordance with the eight shift clocks, and the master station 2 may determine the number as in the above.

In the above-described embodiment, the high level data is used as the predetermined data and the positive logic is used. However, as another embodiment of the present invention, the low level data is used as the predetermined data and the negative data is used. It may be configured by logic.

Next, a normal operation procedure after the registration of the number of vehicles is completed as described above will be described with reference to FIG.

[0055] In this embodiment, first, the input device ₄₁ to ₃
A command to input the ON / OFF state signal of _{No. 1} to each slave station 3 _{1 to} 3 ₄ is transmitted, and accordingly, for example, FIG.
As shown in, each of the slave stations 3 _{1 to} 3 ₃ fetches the data of the input device into the 1-bit shift registers 22 _{1 to} 22 ₄ via the input latch circuit 20 as an input unit. At this time, the end station 3 ₄ does not have an input latch circuit, and the data in the shift register 22 ₄ remains unchanged. Next, in synchronism with the eight shift clocks following the command to transmit the data of the slave stations 3 _{1 to} 3 ₄ to the master station 2, the fetched data is converted into the data shown in FIG. The data is transmitted to the input / output register 11 of the master station 2, and the master station 2
The transmitted data is output to the programmable controller 1.

Next, as to synchronize the data of the master station 2 to the command eight shift clocks subsequent to the event to 3 ₄ transmitted to the slave station 3 _1, shown in the figure (C), O return the data of the register 11 to the slave station 3 ₁ to 3 _4, slave station 3 ₁ to 3 ₄
Each slave station 3 ₁ according to the command to output the data
To 3 ₄ and latches output data of the shift register 22 ₁ to 22 ₄ to the output latch circuit 24 as shown in FIG. (D). In this embodiment, since the output device is not connected, the display LED 23 remains on or off depending on the data.

Therefore, the on / off state of the input devices 4 ₁ to 4 ₃ can be grasped by the display LED 23, and
Depending on the off state of the input device ₄₁ to _3, the display LE
By confirming that D23 is turned on or off, it can be confirmed that the data transmission between the master station 2 and the slave stations 3 _{1 to} 3 ₃ is normally performed.

The end station 3 ₄ latches the data of the shift register 22 _{4 in} the output latch circuit 24 in response to the command to output the data of the slave station.
As shown in the block diagram of FIG. 4, the data latched, applied to the shift register 22 ₄ through the inverter 26, thereby, the shift register 22 ₄ data as shown in FIG. (D) is It will be reversed.

[0059] Then, again, similar to FIG. (A), captures the data of the input device 41 _{to 3} in the shift register 22 ₁ to 22 ₃ of each slave station 3 ₁ to 3 _3, as described above Is repeated. When the data of the input devices 4 ₁ to 4 ₃ is taken in, the data of the shift register 22 ₄ of the end station 3 ₄ remains the inverted data shown in FIG.

As described above, the end station 3 ₄ inverts the data from the master station 2 and sends it back to the master station 2. The master station 2 always inverts the data from the end station 3 _4. The transmission is monitored, and when the inverted data is not transmitted, it is determined that there is an abnormality in the transmission path due to disconnection or noise, and the abnormality output circuit 35 gives a notification output.

[0061] Thus, since always detects the line failure such as disconnection monitoring inversion of data from the end station 3 _4, as compared with the conventional example, so that can respond to rapidly detect the abnormality cause .

[0062] In this embodiment, the end station 3 _4, but configured to send back the data is inverted, as another embodiment of the present invention, the end station, the data from the master station pulse width May be changed and returned.

In this embodiment, in order to easily confirm whether or not the data transmission between the slave stations 3 _{1 to} 3 ₄ and the master station 2 is normally performed, each of the slave stations 3 ₁ to 3 is able to be confirmed. As described above, the check switch 27 as the operation unit is provided in the _4th display LE, and the LE for display for displaying the data from the master station 2 is provided.
D23 is provided.

[0064] Therefore, in the case of confirming whether the transmission of data is performed normally, and turns off the input device ₄₁ to ₃ connected to the slave station 3 ₁ to 3 ₄ to be confirmed First, the check switch 27 is operated. As a result, the high-level monitor data is fetched into the 1-bit shift registers 22 _{1 to} 22 ₄ and transmitted to the master station 2 according to the above-described operation, and the master station 2 returns the data and shifts the data. Given to registers 22 _{1 to} 22 ₄ ,
The high level data of the shift registers 22 _{1 to} 22 ₄ is latched by the output latch circuit 24 and the display LED 23
Will light up.

Therefore, if the check switch 27 is operated to turn on the display LED 23, it can be determined that the LED is normal.

In the above-mentioned embodiment, the case where only the input devices 4 ₁ to 4 ₃ such as various sensors are connected to the respective slave stations 3 _{1 to} 3 ₃ for input only is explained, but another embodiment of the present invention. as a sub-stations 3 ₁ to 3 ₃ to the actuator or air valve or the like output device only connected when the output-only and each slave station 3 ₁ to 3 ₃ to an input device or output device is connected the output combination of The case will be described.

Since the transmission procedure is different between input only, output only and input / output mixed, the manufacturer or the user operates the setting unit (not shown) of the master station 2 to input only, output only or input / output mixed. One of these is to be initialized. Further, in any case, the registration of the number of slave stations is the same as that in the above-mentioned embodiment, and therefore its explanation is omitted.

FIG. 10 is a diagram corresponding to FIG. 9 in the case of output only.

First, a command for inputting the data of the input latch circuit 20 to each of the slave stations 3 _{1 to} 3 ₃ is transmitted, and in response thereto, as shown in FIG. ₁ to ₃
Is a command to fetch the data of the input latch circuit 20 to which the input device is not connected to the 1-bit shift registers 22 _{1 to} 22 ₃ respectively and to transmit the data of the slave stations 3 _{1 to} 3 ₄ to the master station 2. In synchronism with the eight shift clocks following, the captured data is transmitted to the input / output register 11 of the master station 2 as shown in FIG.
As shown in FIG. 2C, the on / off control signal from the programmable controller 1 is loaded into the input / output register 11.

Next, in synchronization with eight shift clocks following the command to transmit the data of the master station 2 to the slave stations 3 _{1 to} 3 ₄ , as shown in FIG. transmitting the data of the register 11 to the slave station 3 ₁ to 3 _4, slave station 3 ₁ to 3 ₄
Each slave station 3 ₁ according to the command to output the data
To 3 _4, as shown in Fig. 2 (E), and outputs the latched data in the shift register 22 ₁ to 22 ₄ to the output latch circuit 24 to an output device such as an actuator. The end station 3 ₄ inverts the data in the shift register 22 ₄ in response to the command to output the data from the slave station.

After that, the data of the input latch circuit 20 is again fetched into the shift registers 22 _{1 to} 22 ₃ of the respective slave stations 3 _{1 to} 3 ₃ and the same operation as described above is performed, as in the case of FIG. It repeats.

FIG. 11 is a diagram corresponding to FIG. 9 in the case of mixed input and output. In this embodiment, input devices are connected to the _first and third slave stations 3 ₁ and 3 ₃ from the upstream side. The output device is connected to the _second slave station 3 ₂ .

First, a command for inputting the data of the input latch circuit 20 to each of the slave stations 3 _{1 to} 3 ₃ is transmitted, and in response thereto, as shown in FIG. _{1-3 4}
Captures the data of the input latch circuit 20 into the 1-bit shift registers 22 _{1 to} 22 ₃ , respectively, and the slave stations 3 ₁ to
As shown in FIG. 2B, the input data of the master station 2 is input and output in synchronization with the eight shift clocks following the command to transmit the data of 3 ₄ to the master station 2. Then, the master station 2 outputs the transmitted ON / OFF state signal from the input device to the programmable controller 1, and then, as shown in FIG. The control signal is taken into the input / output register 11.

Next, in synchronism with eight shift clocks following the command to transmit the data of the master station 2 to the slave stations 3 _{1 to} 3 ₄ , as shown in FIG. transmitting the data of the register 11 to the slave station 3 ₁ to 3 _4, in accordance with a command and should output the data of the slave station, the slave station 3 ₁ to 3 _4,
As shown in FIG. 8E, the shift registers 22 ₁ ...
The data of 22 ₄ is latched by the output latch circuit 24 and output to an output device such as an actuator. In addition, end station 3
₄ responds to the command to output the data of the slave station,
The data in the shift register 22 ₄ is inverted.

After that, the data of the input latch circuit 24 is again fetched into the shift registers 22 _{1 to} 22 ₄ of the respective slave stations 3 _{1 to} 3 ₄ and the same operation as described above is repeated, as in the case of FIG. Of.

In each of the above embodiments, the master station 2 has a maximum of eight.
Although the slave stations could be connected to each other, the present invention is not limited to eight, and it is needless to say that 16 or any other number can be connected.

In each of the above-described embodiments, the power supply lines from the master station 2 are connected in cascade to connect the slave stations 3 _{1 to} 3 ₄ and the slave stations 3 to each other.
_Although power is supplied to the input devices 4 ₁ to 4 ₃ connected to _{1 to} 3 ₃ , as shown in FIG. 12, when the number of slave stations increases and the distance to the downstream slave stations increases, In the slave station on the downstream side, sufficient power is not supplied to the input device or the output device. Therefore, it is necessary to separately provide a power source for each slave station.

Therefore, as another embodiment of the present invention, FIG.
3, the child station 3n on the most downstream side from the parent station 2
In addition to the power supply line VL1 cascade-connected to each other, for example, the power supply line VL2 may be directly connected from the most downstream child station 3n to the parent station 2.

As a result, the double transmission distance can be secured without using a separate power source for each slave station.

Although the end station is provided on the most downstream side in the above-mentioned embodiment, as another embodiment of the present invention, the end station is constructed so that the slave stations can be connected in cascade also on the downstream side thereof.
It may be arranged on the upstream side. In this case, the master station may be configured to be able to set which is the end station, and the master station may select a slave station that is processing data by transmitting data multiple times. It may be configured so that it is recognized as an end station.

Further, an input device or an output device may be connected to the end station.

[0082]

As described above, according to the present invention, at the time of system startup, the number of slave stations connected to the master station is automatically registered, and the number of slave stations connected to the master station is automatically registered. Since the position of the slave station is specified depending on whether or not the slave station is connected to, the work of setting an address number or registering the number of each slave station as in the conventional example becomes unnecessary.

Further, according to the present invention, at least one slave station performs predetermined processing on the data transmitted from the master station and then returns the data to the master station, and the master station performs the predetermined processing. Since the abnormality is detected based on whether or not the transmitted data is returned, it is possible to immediately detect the abnormality in the transmission line such as the disconnection between the master station and the slave station.

Further, according to the present invention, it is confirmed whether or not the display section of the slave station is being displayed according to the state of the input device connected to the slave station or the operation of the operation section of the slave station. By doing so, it is possible to know whether or not the data is normally transmitted between the slave station and the master station, and therefore, as in the conventional example, the workers are respectively assigned to both the slave station side and the master station side. No need to place and check.

Further, according to the present invention, in addition to the power supply line cascade-connected from the master station to each slave station, the slave station on the downstream side and the master station are connected by different power supply lines. Even if a plurality of slave stations are connected and the distance between the slave stations on the downstream side and the master station is large, sufficient power can be supplied.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a master station of FIG.

FIG. 3 is a block diagram of a slave station in FIG.

4 is a block diagram of the end station of FIG. 1. FIG.

FIG. 5 is a signal waveform diagram when data is transmitted from a master station to a slave station.

FIG. 6 is a signal waveform diagram when data is transmitted from a child station to a parent station.

FIG. 7 is a diagram showing data in a register when registering the number of vehicles.

FIG. 8 is a signal waveform diagram for explaining determination of the number of vehicles.

FIG. 9 is a diagram showing register data during normal operation.

FIG. 10 is a diagram showing register data at the time of normal operation of another embodiment of the present invention.

FIG. 11 is a diagram showing register data during normal operation according to still another embodiment of the present invention.

FIG. 12 is a diagram showing power supply in the embodiment of FIG.

FIG. 13 is a diagram showing power supply according to another embodiment of the present invention.

FIG. 14 is a configuration diagram of a conventional example.

[Explanation of symbols]

2 Master station 3 _{1 to} 3 ₄ Slave station 4 ₁ to 4 ₃ Input device 23 LED for display 27 Check switch

Claims (8)

[Claims] 1. A master station and a plurality of slave stations are connected in cascade, and data of the master station is sequentially shifted from an upstream slave station on the master station side to a downstream slave station. In the control communication system for transmitting the data of the slave station to the master station by sequentially shifting the data of the slave station from the slave station on the downstream side to the slave station on the upstream side, wherein the master station is a predetermined data Is transmitted to the plurality of child stations, the respective child stations are specified based on the data returned from the plurality of child stations. 2. A master station and a plurality of slave stations are connected in cascade, and data of the master station is sequentially shifted from an upstream slave station on the master station side to a downstream slave station. To the master station by sequentially shifting the data of the slave station from the slave station on the downstream side to the slave station on the upstream side, wherein the master station is the plurality of A control communication system characterized in that each slave station is specified based on predetermined data transmitted from the slave station. 3. The control communication system according to claim 1, wherein the master station identifies each slave station by obtaining the number of slave stations. 4. At least one slave station of the plurality of slave stations performs predetermined processing on the data transmitted from the master station, and then returns the data to the master station. The control communication system according to any one of claims 1 to 3, wherein an abnormality is detected based on whether or not the data subjected to the predetermined processing is returned. 5. The control communication system according to claim 4, wherein the at least one slave station is a slave station on the most downstream side. 6. The slave station has a display section for displaying according to the data transmitted from the master station, and an input section for inputting data from an input device connected to the slave station. 6. The control communication system according to claim 1, wherein the data transmitted from the input unit is transmitted to the master station, and the master station returns the data transmitted from the slave station. 7. The slave station has an operation unit that is operated to confirm whether or not data is normally transmitted, and a display unit that displays according to the data transmitted from the master station. At the same time, the monitor data according to the operation of the operation unit is transmitted to the master station, and the master station returns the monitor data transmitted from the slave station. Control communication system. 8. Apart from a power supply line cascade-connected to supply power to each slave station from the master station to the most downstream slave station, directly from the downstream slave station to the master station, The control communication system according to claim 1, wherein a power supply line is connected.