YOKOGAWA RS422/RS485 Module ALR121-S00

Models ALR111 and ALR121 Serial Communication Modules used with a safety control station (SCS) for performing Modbus communication.

By using the SCS’s Modbus slave communication function, the data in SCS can be set or referred to by the Modbus master which is as separate system from SCS via a serial communication module. Furthermore, the subsystem

data such as from sequencers can be set or referred to via a serial communication module using SCS’s subsystem communication function.

These serial communication modules can be mounted on a safety control unit and a safety node unit.

Hardware specifications of ALR111 and ALR121 serial communication modules are as shown below. These modules are interference-free modules that have no interference with the safety loop.

Table Serial Communication Module Hardware Specifications

Item	Specifications
Model	ALR111	ALR121
Interface	RS-232C	RS-422/RS-485 (4-wire system)
Connection method	Point-to-point	Point-to-point (RS-422) Multipoint (RS-485)
Communication function	Half-duplex
Synchronization method	Start-stop synchronization
Transmission speed	1200/2400/4800/9600/19200/38400 bps
Transmission code	binary
Character length	8 bits (Fixed to 8 bit on the Modbus slave communication function and the subsystem communication function)
Stop bit length	1/2 bits (Fixed to 1 bit on the subsystem communication function)
Parity check	None/even/odd
Lag time after data transmission	1 ms
Transmission distance	Maximum 15 m	Maximum 1200 m (total extended length)
Installation method	Mounted on S2SC70 , SSC60 , SSC50 , SSC57 , or SNB10D
I/O wiring	AKB131, AKB132, AKB135, AKB136 cables, etc.	Cable with 3-pair shield, AKB161, or AKB162
Wiring connection	D-sub-9-pin (female × 2 ports)	Clamped with terminal block’s M4 screws (5 poles × 2 ports)
Communication function (*1)	Modbus slave communication function, subsystem communication function
Current consumption	0.5 A	0.5 A
Weight	Approx. 0.3 kg	Approx. 0.34 kg

*1: A unit of SCS is capable of handling multiple communication functions: however, different types of communication functions cannot be simultaneously performed on a serial communication module. It means that two ports must have identical

communication functions.

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