The A1SJ71(U)C24 computer link module provides a serial communication link to a Mitsubishi A-Series PLC Device. Fernhill SCADA can use this module to monitor and control a Mitsubishi A-Series PLC Device.
The information in this guide applies to a range of Mitsubishi Melsec A-Series computer link modules:
Module | Interface |
---|---|
A1SJ71UC24-R2 | RS-232 computer link module |
A1SJ71UC24-R4 | RS-422/485 computer link module |
A1SJ71C24-R2 | RS-232 computer link module |
A1SJ71C24-R4 | RS-422/485 computer link module |
The rest of this article uses the name A1SJ71C24 to refer to any of the above modules.
There are two types of connection on the A-Series serial communication modules:
Connection Type | Description |
---|---|
RS-232 DE-9 | RS-232 using a D-Subminiature 9 pin female connector |
RS-422/485 Screw Terminals | RS-422/485 using a screw terminals |
The RS-232 port on an A1SJ71C24 can connect directly to a serial port on a PC. The serial port on a PC is usually a 9 pin D-subminiature connector. To connect the A1SJ71C24 to a PC, a connection cable with this wiring is required:
A1SJ71C24 RS-232![]() |
PC![]() | ||
---|---|---|---|
RXD | 2 | 3 | TXD |
TXD | 3 | 2 | RXD |
DTR | 4 | 6 | DSR |
GND | 5 | 5 | GND |
DSR + DCD | 6 + 1 | 4 | DTR |
RTS | 7 | 8 | CTS |
CTS | 8 | 7 | RTS |
Note: All other pins not shown in the above diagram have no connection.
Use this table to select the appropriate wiring between the screw terminals on the module and common RS-422 adapters:
Mitsubishi Melsec | ||||
---|---|---|---|---|
RDA | RDB | SDA | SDB | |
Advantech ADAM-4520 | TX+ | TX- | RX+ | RX- |
StarTech IC485S IC485SGB IC485SEU | 1 (TX-) | 2 (TX+) | 4 (RX-) | 3 (RX+) |
For more information about connecting a PLC Device to a computer using an RS-422 link, see RS-422 Communication with PLC Devices.
Setting up a serial communication link can be difficult because of the wide variety of communication options. For example:
For Fernhill SCADA to communicate with an A1SJ71C24 module, both need to use the same communication options. There are two ways to do this:
The A1SJ71C24 module is configured by front panel switches.
Fernhill SCADA is configured using properties of the Channel and PLC tags:
The relationship between A1SJ71C24 front panel switches and Fernhill SCADA properties is:
A1SJ71C24 Switch | Fernhill SCADA Property |
---|---|
Station No | StationNumber in the Mitsubishi Melsec PLC Tag |
Mode | CommFormat in the Mitsubishi Melsec serial channel |
SW05-SW11 | Mode in the Mitsubishi Melsec serial channel |
Note: The Station No switch is not fitted to the R2 variants of the module.
The rest switches on the A1SJ71C24 Computer Link module should be set to these positions for correct operation:
A1SJ71C24 Switch | Setting |
---|---|
SW03 | Off |
SW04 | On (Allow write during RUN) |
SW12 | On (Use sum check) |
The StationNumber property of the Mitsubishi Melsec PLC Tag should be set as follows:
The Mode Switch can be set to 1, 2, 3 or 4. The CommFormat property of the Mitsubishi Melsec serial channel should be set to the matching value:
Mode Switch | CommFormat |
---|---|
1 | Format 1 |
2 | Format 2 |
3 | Format 3 |
4 | Format 4 |
SW05 to SW07 define the baud rate of the communication channel. The Mode property of the Mitsubishi Melsec serial channel should contain a matching Baud clause:
SW05 | SW06 | SW07 | Mode String Clause |
---|---|---|---|
Off | Off | Off | Baud=300 |
On | Off | Off | Baud=600 |
Off | On | Off | Baud=1200 |
On | On | Off | Baud=2400 |
Off | Off | On | Baud=4800 |
On | Off | On | Baud=9600 |
Off | On | On | Baud=19200 |
SW08 defines the number of data bits in each character transmitted on the communication channel. The Mode property of the Mitsubishi Melsec serial channel should contain a matching Data clause:
SW08 | Mode String Clause |
---|---|
Off | Data=7 |
On | Data=8 |
SW09 and SW10 define the parity bit added to each character transmitted on the communication channel. The Mode property of the Mitsubishi Melsec serial channel should contain a matching Parity clause:
SW09 | SW10 | Mode String Clause |
---|---|---|
Off | * | Parity=N |
On | Off | Parity=O |
On | On | Parity=E |
Note: The asterisk (*) means not applicable.
SW11 defines the number of stop bits in each character transmitted on the communication channel. The Mode property of the Mitsubishi Melsec serial channel should contain a matching Stop clause:
SW11 | Mode String Clause |
---|---|
Off | Stop=1 |
On | Stop=2 |
For more information refer to the A1SJ71C24 User Manual.
Mitsubishi Melsec Serial Autodetect Wizard
For how to automatically configure Fernhill SCADA to communicate with a Mitsubishi serial communication module.
Mitsubishi Melsec serial channel
For information about Mitsubishi Melsec serial channel configuration.
For information about Mitsubishi Melsec PLC Tag configuration.
For background information on serial communications.
For information about the Mitsubishi Melsec Driver.
For the meaning of terms used in Fernhill SCADA.