JPH0537569Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of the invention] The present invention is a multiplex transmission device configured by connecting a primary station (master station) and a plurality of secondary stations (slave stations) in a multi-drop manner using two-core wires. This concerns the primary station.

[Prior art and its problems]

(Prior art) In general, in a time-division multiplex transmission device that configures a data transmission system by connecting a primary station and a plurality of secondary stations using a two-core dedicated line, each secondary station has its own unique Set the address and 1 based on that address.
Data is transmitted between the next station and the secondary station. Then, in the primary station of the multiplex transmission equipment, in order to detect a failure in the secondary station connected to the transmission line or an abnormality in the transmission line, a certain amount of data is sequentially sent to each secondary station, and the data is sent back to the secondary station. The test polling process received from the station may be performed. In addition, the primary station performs a transmission abnormality judgment process to check whether the expected response is transmitted from the secondary station during normal data transmission, but the primary station performs transmission abnormality judgment processing to check whether the expected response is transmitted from the secondary station during normal data transmission. It is necessary to start it. The start of these test polling and the return from the stopped state are each performed by separate switches.

(Problems to be Solved by the Invention) However, such conventional multiplex transmission equipment has the disadvantage that it is prone to erroneous operation because it requires two switches, one for test polling and one for returning from a stop. Another problem is that the price increases because it is necessary to provide two switches independently.

[Purpose of invention]

The present invention has been developed in view of the problems of conventional multiplex transmission equipment, and aims to enable a single switch to start test polling processing and return to a data transmission state in the event of a transmission error. is a technical issue.

[Structure and effect of the idea]

(Means for Solving the Problems) The present invention is a primary station of a multiplex transmission device in which a primary station and a plurality of secondary stations are connected by transmission lines. A data transmission means 1 that performs transmission and reception with a secondary station; a switch means 2 that provides a switch signal; a test polling means 3 that performs a test polling process of sequentially transmitting data and receiving the data; and a transmission means that stops transmission if an abnormality occurs during test polling by the test polling means or during data transmission by the data transmission means. a stop means 4; and a transmission return means 5 for returning to the data transmission state when a switch signal is given from the switch means while the transmission is stopped by the transmission stop means.
It is characterized by comprising the following.

(Function) According to the present invention having such characteristics, the primary station uses a single switch to perform test polling processing to detect the connection status of each secondary station and recovery from an abnormality. . If the switch is pressed during normal operation, test polling processing is executed only while the switch is pressed. If this switch is not pressed, normal data transmission is performed, and if there is an abnormality during data transmission or test polling, transmission is stopped. If this switch is pressed while transmission is stopped, the device returns from that state and starts data transmission again.

(Effect of the invention) Therefore, according to the invention, one switch can
Since only one operation can be performed, the number of parts can be reduced, the failure rate can be reduced, and manufacturing can be facilitated. Furthermore, since a single switch is used to perform processing when necessary, it is possible to reduce the number of erroneous operations.

[Explanation of Examples]

FIG. 2 is a schematic block diagram showing an embodiment of a multiplex transmission device according to the present invention. In the figure, a programmable controller 12 which is a higher level control device is connected to the primary station 11. Primary station 11
A two-core transmission line 13 is connected to its input terminal, and a plurality of secondary stations 14a to 14e are connected to this transmission line 13 at arbitrary points in a multi-drop manner. 1
The next station 11 sequentially sends address and data signals to each of the secondary stations 14a to 14e, receives the data signal received from the transmission line 13, and performs data transmission with each of the secondary stations.

Next, FIG. 3 is a block diagram showing an example of a primary station according to the present invention. In the primary station 11 shown in the figure, a CPU 22 is connected to a programmable controller 12 via a PC interface circuit 21. The CPU 22 has a memory 23 which is a storage means.
is connected, and I/O interface circuit 2
4. A communication interface circuit 25 is connected. The CPU 22 transmits address and data signals to each secondary station according to a predetermined processing program stored in the memory 23, and performs data transmission with each secondary station. Connected to the communication interface circuit 25 are a driver that sends signals to the transmission line 13 and a driver/receiver circuit 26 that receives data from each secondary station. The I/O interface circuit 24 lights up when there is a transmission error.
LED1 and LED2, which lights up when the test is successfully completed during test polling processing, are connected.
Further, one end of a dual-purpose switch SW1 is connected to the I/O interface circuit 24, which is turned on at the start of test polling and at the time of recovery from an abnormal state. The switch SW1 is a momentary type push button switch whose other end is connected to a power supply via a pull-up resistor, and is used to execute test polling and to provide a signal for returning from a transmission halt state.

Each secondary station has its own unique address set, and performs data transmission with the primary station when a command or data signal is obtained following that address from the primary station 11. A plurality of input/output elements such as relays, photoelectric switches, proximity switches, etc. are connected via input/output circuits.

Next, the operation of this embodiment will be explained with reference to a flowchart. In the flowchart shown in FIG. 4, when the operation starts, the routine 31
, the CPU 22 performs data transmission with each of the secondary stations 14a to 14e. Here, the CPU 22 achieves the function of the data transmission means 1 for transmitting data between each secondary station after starting operation in the routine 31. When one cycle of data transmission is completed, the process advances to step 32 to check whether the dual-purpose switch SW1 is turned on. switch
If SW1 is not turned on, the process advances to step 33 and the light emitting diode LED2 is turned off. The process then proceeds to routine 34, where it is determined whether a normal response has been received from each secondary station as a result of data transmission. If there is no transmission error, proceed to steps 36 and 37 via step 35, turn off the light emitting diode LED1 for indicating transmission error, clear the transmission error error counter N, and return to routine 31 to repeat the same process. .

If a transmission abnormality is determined in routine 34, the process advances to step 38 via step 35, and an error counter N is incremented. Then, the process advances to step 39 to check whether the error count number N has reached 3. If it has not reached 3, the process returns to routine 31 and repeats the data transmission process. If the error counter N reaches 3 in step 39, the process proceeds to steps 40 and 41, where the LED 1 for indicating a transmission error is turned on and the transmission is stopped.
Then, switch SW1 is turned on and checks whether it changes from off to on (step 42).
If there is no change, the process returns to step 40 to continue the transmission stopped state. When the dual-purpose switch SW1 is turned on, the process proceeds from step 42 to step 37, where the error counter N is cleared, and the process proceeds to routine 31, where transmission execution is resumed.

Now, if the dual-purpose switch SW1 is turned on during execution of transmission, after execution of routine 31 to end transmission, the routine proceeds from step 32 to routine 43, where test polling processing is executed. The test polling process is performed for each secondary station 14a connected on the transmission line 13.
~14e, and receives the processed data from each secondary station to check whether there is any abnormality in the transmission line 13 and each secondary station. 32, 43
The test polling means 3 performs a test polling process of transmitting a predetermined signal to each secondary station and receiving data when a switch signal is applied during transmission by the data transmission means. There is. If there is no abnormality in the test polling, the process advances to step 45 via step 44, lights up the light emitting diode LED2 indicating that there is no abnormality in the test polling, and returns to step 32. However, if an abnormality is determined during the test polling, the process proceeds from step 44 to step 46, and the LED 2, which indicates that the test polling is normal, is turned off. Then proceed to steps 40 and 41, where the LED indicating transmission abnormality
Turn on 1 to stop transmission. Here CPU22
is routine 34, steps 35-41 and steps
44 and 46 achieve the function of the transmission stop means 4 that stops the transmission when an abnormality occurs during test polling or data transmission. In this way, if an abnormality is determined by this test polling, the loop of steps 40 to 42 is repeated and transmission is stopped, but if the dual-purpose switch SW1 is turned on during this time, the process returns from step 42 to step 37 and the error counter N is Clear and resume transmission execution. Here, the CPU 22 achieves the function of the transmission return means 5 which returns to the data transmission state when a switch signal is applied from the switch means during transmission stop in steps 40-42. As described above, in the present invention, one switch has the function of inputting the start of test polling and the function of inputting the restart of data transmission in the event of an abnormal stop.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the functional configuration of the present invention, FIG. 2 is a block diagram showing an example of a multiplex transmission device to which the primary station of the present invention is applied, and FIG. 3 is a block diagram of the primary station of the present embodiment. FIG. 4 is a flowchart showing the operation of the primary station of this embodiment. 1... Data transmission means, 2... Switch means,
3...Test polling means, 4...Transmission abnormality detection means, 11...Primary station, 12...Programmable controller, 13...Transmission line, 14a-14
e...Second station, 22...CPU, LED1, LED2
...Light emitting diode, SW1...Dual-purpose switch.

Claims (1)

[Scope of Claim for Utility Model Registration] A data transmission means that is a primary station of a multiplex transmission device in which a primary station and a plurality of secondary stations are connected by a transmission line, and that performs transmission and reception with each secondary station; switch means for giving a switch signal; and test polling for sequentially sending a predetermined signal to each of the secondary stations and receiving the data when the switch signal is given from the switch means during transmission by the data transmission means. test polling means for performing processing; transmission stop means for stopping transmission when an abnormality occurs during test polling by the test polling means and data transmission by the data transmission means; A primary station of a multiplex transmission apparatus, comprising: transmission return means for returning to a data transmission state when a switch signal is applied from the switch means.