Mitsubishi A1SJ71(U)C24 Connection Guide

Introduction

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

Connection Cables

RS-232 Connection

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.

RS-422 Connections

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.

Configuring Serial Communications

Setting up a serial communication link can be difficult because of the wide variety of communication options. For example:

Baud Rate
Frame Format
Protocol

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 easiest way is to use the Mitsubishi Melsec Serial Autodetect Wizard. Using the options you select, the wizard will try different settings to work out the correct Fernhill SCADA configuration.
Manually configure Fernhill SCADA and the A1SJ71C24 module to use the same communication options.

Manual Configuration

The A1SJ71C24 module is configured by front panel switches.

Fernhill SCADA is configured using properties of the Channel and PLC tags:

The Mode and CommFormat properties on the Mitsubishi Melsec serial channel.
The StationNumber property on the Mitsubishi Melsec PLC Tag.

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)

Station No

The StationNumber property of the Mitsubishi Melsec PLC Tag should be set as follows:

For modules ending with R4, the StationNumber property should match the Station No switch on the front panel.
For modules ending with R2, the StationNumber property should be set to 0 (zero).

Mode Switch

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

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

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

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

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.

Further Information

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.

Mitsubishi Melsec PLC Tag

For information about Mitsubishi Melsec PLC Tag configuration.

Serial Communications

For background information on serial communications.

Mitsubishi Melsec Driver

For information about the Mitsubishi Melsec Driver.

Glossary

For the meaning of terms used in Fernhill SCADA.