JP3388246B2 - Remote I / O system for programmable controller - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a remote I / O of a PC comprising a master station connected to a programmable controller (hereinafter referred to as a PC) and a slave station connected to the master station.
Regarding the O system.

[0002]

2. Description of the Related Art When controlling a plurality of devices dispersed in a factory or the like with a single PC, it is necessary to connect several tens of input / output wires from the PC to each device, which makes wiring work complicated. And problems such as increased installation work will occur. In order to solve this problem, a PC remote I / O system configured as shown in FIG. 8 was devised for the purpose of wire saving.

The remote I / O system of a PC is a CPU
A master station 2 that is built into a PC in the same manner as the unit (hereinafter referred to as the PC main body) 1 and the input / output units (I / O units) 1a and 1b, and is directly connected to the PC main body 1 and the like via a CPU bus The master station 2 and one or a plurality of slave stations 3 connected via a communication cable 4 such as a coaxial cable or an optical fiber.

[0004] Each slave station 3 is usually a plurality of input-output unit 3a via the data bus, 3b are connected, each input-output units 3a, 3b to the motor and switches (S
W), a controlled device such as a sensor are connected, and the PC body 1 is configured to control a remote non-controlled device.

The remote I / O of the PC configured as described above
The O systems, input and output units 3a on the remote station 3 PC main body 1 via the master station 2, when controlling 3b, and the input data on the slave station 3 to the PC 1 via the master station 2, the PC 1 the output unit 3b on the slave station 3 via the parent station 2 the output data of the
Need to output to.

Here, the data communication method between the PC body 1 and the present system includes a method for executing instruction execution and communication processing in synchronization with execution of a remote input / output instruction in a command word of the PC body, and a fixed time or There is a method of asynchronously performing the end refresh timing, which is called remote refresh processing.

Further, data transmission and reception between the master station and the slave station is normally polling / selection by the master station, i.e. sends a polling frame to set the output data in the order of the node number to each slave station, the polling frame This is performed by the received slave station setting the input data in the response frame and returning it to the master station.

[0008]

[SUMMARY OF THE INVENTION Incidentally, in such a conventional remote I / O system, sequentially transmits the polling frame to each slave station, receives input data and transmits the output data for each slave station As a result, the polling cycle time increases, data cannot be exchanged at high speed between the master station and the slave station, which affects the instruction execution time of the PC main unit and the I / O unit connected to the slave station. Has the problem that it cannot be accessed like the I / O unit on the PC body.

Therefore, the present invention has been made to solve the above problems, and provides a remote I / O system for a PC which can shorten the polling cycle time and speed up data exchange between a master station and a slave station. The purpose is to do.

[0010]

In order to achieve the above object, the present invention provides a programmable controller for controlling a controlled device.
A master station directly connected to the controller and a slave station connected to the master station via a communication cable and to which a plurality of input units are connected. The master station is programmable by polling / selection method. Con
While sending the output data from the tracker to each slave station,
A programmable controller that allows each slave station to receive input data captured via the input unit and to enable the programmable controller to refresh the input / output data.
In the remote I / O system of the controller , the master station has an output data memory for storing output data to be transmitted from the programmable controller to the slave station,
The output change flag that sets the output change flag when the output data stored in the output data memory is compared with the output data sent to the slave station at the previous polling and the value of the data has changed. setting means, it is determined whether or not the output change flag is set by the output change flag setting means, the output change flag output data into play <br/> if it is set that is stored in the output data memory Is set in the polling frame and transmitted, and when the output change flag is not set, the polling means transmits the output data without setting it in the polling frame. Input data memory that stores the input data captured via the The input change flag setting means for setting the input change flag when the value of the data is changing, and whether or not the input change flag is set by the input change flag setting means. it is determined, while returning set the input data stored in said input data memory in response frame if the input change flag is set, when the input change flag is not set the input data It is characterized by comprising a response means for returning without setting in a response frame.

[0011]

In the present invention, the master station compares the output data, which is stored in the output data memory and should be transmitted to the slave station this time, with the stored output data transmitted at the previous polling. , If the data value has changed, set the output data in the polling frame and send it. If the data value has not changed, send the output data without setting it in the polling frame. .

In the slave station , when the input data stored through the input unit and stored in the input data memory is compared with the stored input data returned at the previous polling, and the value of the data has changed. Only, the input data is set in the response frame and returned, and when the data value does not change, the input data is returned without being set in the response frame.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a PC remote I / O system according to the present invention will be described below with reference to the drawings.

FIG. 1 shows the remote I / O of the PC of this embodiment.
The system configuration is shown.

This system is built into a PC in the same manner as the PC body 1 and the input / output unit (see FIG. 8).
And the like, and one or a plurality of units connected to the master station 2 via a communication cable 4 such as a coaxial communication cable or an optical fiber (one unit for convenience in this figure). composed of slave station 3 which the only shown).

The PC main body 1 controls a machine or device such as a motor through an input / output unit (see FIG. 8) directly incorporated in the PC and input / output units 3a and 3b connected to the present system. In this figure, only the MPU 11 that executes communication with the system, that is, remote refresh is shown.

The master station 2 transmits / receives data to / from the PC body 1 via the CPU bus, and controls communication by polling / selection with the slave station 3 via the communication cable 4 as output change flag setting means and polling means. The MPU 21 has a shared RAM 23 that exchanges output data and input data with the PC body 1, and a communication LSI 22 that has a transmission / reception buffer (not shown) and that communicates with the slave station 3. A0 is a remote refresh request signal for requesting the master station 2 to write and read input / output data to the PC body 1, and A1 is transmitted from the PC body 1 to the master station 2 when the access to the shared RAM 22 is completed. This is a remote refresh completion signal.

The slave station 3 functions as an input change flag setting means and a response means via the communication cable 4 to control communication with the master station 2 and data transmission / reception with the input / output units 3a and 3b, and a transmission / reception buffer (not shown). No)
It has a communication LSI 32 that has a built-in device and communicates with the master station 2, and an input data memory 33 that captures the value of an input pulse input via the input unit 3a and stores it as input data.

FIG. 2 shows a detailed structure of a polling frame or a response frame transmitted / received between the master station 2 and the slave station 3.

This communication frame includes, for example, a preamble (P) of about 1 byte and a synchronous character (S).
YN), address (ADRS), control field (CNF), and frame check sequence (FCS) of about 2 bytes, and data (DATA) of about several tens to 1000 bytes. Then, in the case of the polling frame, the control field (CN
In F), a transmission command for instructing the slave station to fetch output data and a reception command for instructing setting of input data are set in the response.

3 (a) and 3 (b) show the setting procedure of the input change flag and the output change flag, respectively.

(A) shows an example of setting the input change flag in the MPU 31 of the slave station 3. The MPU 31 receives the polling frame from the master station 2 and the input data "00101101" of this time and self Input data “0000” returned by the previous polling stored in
1101 ", and when the data value is different between the previous time and this time, that is, when the input data is changed,
While the input change flag is set to "1", if the input data has not changed, the input change flag is set to "0" and held in a register or the like.

[0023] It should be noted that, even MPU21 of the parent station 2 In the same manner, as shown in (b), slave station 3 during this time of polling
The output data "10010101" to be transmitted, itself compares the output data "11010101" which is transmitted to the slave station 3 during the previous polling the stored,
When the output data has changed, the output change flag is set to "1", while when the output data has not changed, the output change flag is set to "0" and held in the register.

Next, the operation of the present system thus constructed will be described.

FIG. 4 shows the procedure of polling / selection communication processing in the master station 2.

[0026] In this figure shows the communication process between the master station 2 and the three slave stations A through C, shows particularly communicate with the slave station A (step 100) in greater detail.

Firstly, in this process, performs predetermined communication start process of the slave station A (step 110), the output change flag indicating the change of the output data to the slave station A which is stored in the aforementioned register or the like determination (step 120), if the output change flag is set to "1" (step 120 "Yes"), the output data to be transmitted to the slave station a during the current polling, the at the previous poll Since it indicates that the output data is different from the output data transmitted to the slave station A, as shown in FIG. 2, the transmission command and the reception command are set in the control field (CNF) of the polling frame, and the output concerned is set in the polling frame. Set data and send to slave station A (step 13)
0).

On the other hand, when the output change flag is "0" (step 120 "No"), the output data to be transmitted to the slave station A this time is different from the output data transmitted to the slave station A at the time of the previous polling. Since the output data is not set, the output data is not set in the polling frame, but only the reception command is set in the control field (CNF) of this polling frame and transmitted (step 14).
0).

Therefore, in the master station 2, when the output data to be transmitted to the slave station A is not different from the output data transmitted last time, since the output data is not transmitted, only that data is transmitted. The polling frame is shortened and the polling time is shortened.

At the slave station A, although not shown here, the input data is fetched and stored, and the input data is compared with the input data returned at the previous polling. Input change flag is set.

When the polling frame from the master station 2 is received, first, if there is a transmission command in the control field (CNF), the output data is taken in according to the transmission command, while if there is no transmission command, the output data is output. Do not import.

Further, when the input change flag stored in the register or the like is judged according to the received command of the control field (CNF) and "1" is set in the input change flag, that is, the current input data and the previous polling time are set. If the input data returned is different, the slave station A
Sets the input data in the response frame and the master station 2
Return to. On the other hand, when the input change flag is “0”, the slave station A returns the response frame to the master station 2 without setting the input data.

[0033] Therefore, the master station 2, when the input change flag at the slave station A is set to "1" (step 0.99 "Yes"), when the response frame has been sent back from the slave station A While receiving the response and the input data (step 160), if the input change flag is not set to "1" in the slave station A (step 150).
"No"), only the response is received when the response frame is returned from the slave station A (step 17).
0), followed by terminating the communication process with the slave station A (step 180).

Therefore, in the slave station A, when the input data to be returned to the master station 2 is not different from the input data returned at the time of the previous polling, the input data is not returned, and therefore only that data is returned. The response frame is shortened and the polling time is also shortened.

After completion of the communication processing with the slave station A,
Successively the other two slave stations B, C also performs the same communication processing as in the case of the slave station A (step 200, 300), it returns to the communication process again slave station A when finished (step 100).

Next, how much the communication cycle time is shortened by the present system as compared with the conventional system will be described.
And communication between the three slave stations A to C will be described as an example. First, FIG. 5 shows the condition of the output change flag and an input change flag for each slave station A through C. That is, for the slave station A, there is output data transmitted from the master station 2,
In addition, there is also input data to be returned to the master station 2, there is no such input / output data for the slave station B, and there is only input data to be returned to the master station for the slave station C. There is.

When data communication is executed by this system under such conditions, the frame to be communicated and one communication cycle time are as shown in FIG.
In FIG. 7 and FIG. 7, which will be described next, responses such as preamble (P) and synchronous character (SYN) related to commands other than commands and data are omitted.

That is, first, in the frame communicated between the master station 2 and the slave station A, since the output change flag and the input change flag are set to "1" (see FIG. 5), the transmission command, It consists of output (OUT) data, a received command, and an input (IN) command. Here, the communication time in which those frames are combined is Ta.

In the frame communicated with the slave station B, since both the output change flag and the input change flag remain "0" (see FIG. 5), only the receive command is transmitted from the master station. , No output data is sent, and
Since the input data is not returned, only the receive command is available. Therefore, the communication time required for the slave station B is the communication time Tb for only the received command.

Further, in the frame communicated with the slave station C, the output change flag is not set to "1" and the input change flag is set to "1" (see FIG. 5). From the master station, only the received command is set in the polling frame and transmitted, and the input data is set in the response frame and returned. Therefore, child station 3
The communication time required for is the total time Tc of the received command and the input data.

On the other hand, such a condition (see FIG. 5)
When communication is performed by the conventional remote I / O system, the result is as shown in FIG. That is, according to the conventional system, regardless of the value of each the slave station A~C output change flag and an input change flag, respectively, transmission command, output data, receive commands, and the frame of the input data is transmitted.

Therefore, one communication cycle time T = Ta + Tb + Tc according to the present system and 1 according to the conventional system.
Communication cycle time T '= Ta' (Ta) + Tb '+ T
As can be seen by comparing with c ', in this system, when the output data to be transmitted to the slave station is the same as the output data at the time of the previous poll, and the input data to be returned to the master station is at the time of the previous poll. If the input data is the same as the input data of No. 2, the output data and the input data of several tens to several 1000 bytes, which occupy most of the communication frame, are not transmitted as described with reference to FIG. The polling cycle time, that is, the communication cycle time is shortened.

[0043]

As described in the foregoing, in the present invention, the output data to be transmitted to the slave station is not changed as compared to the output data at the time put <br/> Ru previous polling to the slave station in the master station the output data is not sent when also the if the input data to be sent back slave station odor <br/> Te to the master station is not changed as compared to the input data at the time of the previous poll in the slave station Since the input data is not returned, the communication frame is shortened by the output data and the input data, and the communication cycle time between the master station and the slave station is shortened.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a remote I / O system for a PC according to the present invention.

FIG. 2 is an explanatory diagram showing a detailed structure of a communication frame.

FIG. 3A and FIG. 3B are explanatory views showing a procedure for setting input and output change flags, respectively.

FIG. 4 is a flowchart showing a procedure of communication processing in a master station.

Figure 5 is an explanatory view showing the condition of the input and output change flag for each slave station A through C.

FIG. 6 is an explanatory view showing in simplified form a frame communicated by the present system.

FIG. 7 is an explanatory diagram showing in simplified form a frame communicated by a remote I / O system of a conventional PC.

FIG. 8 is an explanatory diagram showing the configuration of a conventional PC remote I / O system.

[Explanation of symbols]

1 PC body 2 parent stations ThreeSlave station 3a Input unit 4 communication cable 21 MPU (output change flag setting means, polling transmission
(Credit means) 23 Shared RAM (output data memory) 31 MPU (input change flag setting means, response return
Sending means) 33 Input data memory A to CSlave station

Claims (2)

(57) [Claims] 1. A programmable controller for controlling a controlled device.
It is composed of a master station directly connected to the controller and a slave station connected to the master station via a communication cable and to which a plurality of input units are connected.
Depending on the selection method, the programmable controller
It transmits the output data from the roller to the respective slave stations, and receives input data each slave station taken via an input unit, a programmable controller that the programmable controller has to be able to refresh the input and output data remote In the I / O system, the master station stores the output data to be transmitted from the programmable controller to the slave station, the output data memory stored in the output data memory, and the slave station at the time of the previous polling. The output change flag is set by comparing the output data sent to the station with the output change flag setting means for setting the output change flag if the value of the data is changing, and whether the output change flag is set by the output change flag setting means. to determine whether the output data if the output change flag is set While the output data stored in the memory is set in the polling frame and is transmitted, the output data is not set in the polling frame and is transmitted when the output change flag is not set. The slave station compares the input data memory that stores the input data fetched via the input unit, the input data stored in the input data memory, and the input data returned at the previous polling, and the data value Is changing, the input change flag is set by the input change flag setting means for setting the input change flag, and whether or not the input change flag is set by the input change flag setting means . In this case, the input data stored in the input data memory is set in the response frame and returned, while the input data is input. A remote I / O system of a programmable controller, comprising: a response unit that returns input data without setting it in a response frame when a change flag is not set. 2. A programmable device for controlling a controlled device
Connectable to controller and polling / selecting
The programmable controller
Output data from these units to the slave unit, and this slave unit
A master station that receives the input data captured via the remote controller, the output data memory that stores the output data to be transmitted from the programmable controller to the slave station, the output data stored in the output data memory, and the previous The output change flag setting means for comparing the output data transmitted to the slave station at the time of polling and setting the output change flag when the value of the data has changed, and the output change flag setting means for setting the output change flag by the output change flag setting means. There it is determined whether or not a set, whereas if the output change flag is set and transmits the set output data stored in the output data memory to the polling frame, the output change flag is not set In this case, a polling means for transmitting output data without setting it in a polling frame is provided. Master station of the remote I / O system of Ramaburu controller.