ALR121-S51 Yokogawa Serial Communication Module

Communication Module | Yokogawa ALR121-S51 S1 RS-422/RS-485

Communication Module | Yokogawa ALR121-S51 S1 RS-422/RS-485

Availability: 20 left in stock

Yokogawa ALR121-S51 Serial Communication Module The Yokogawa ALR121-S51 S1, also cataloged as the ALR121 Serial Communication Module, operates as a...

SKU: ALR121-S51 S1

Manufacturer: Yokogawa
Product No.: ALR121-S51 S1
Product Type: Serial Communication Modules
Product Origin: JAPAN
Payment:T/T, Western Union
Weight: 340g
Shipping port: Xiamen
Warranty: 12 months

Description Reviews

Yokogawa ALR121-S51 Serial Communication Module

The Yokogawa ALR121-S51 S1, also cataloged as the ALR121 Serial Communication Module, operates as a dedicated hardware component for half-duplex serial subsystem interfacing within CENTUM VP and CS 3000 Field Control Station networks.

Suffix Breakdown & Model Matrix

Model / Suffix Code	Specification
ALR121	Serial Communication Module (2-channel, RS-422/RS-485)
-S	Standard type module
5	Standard status display with single slot mounting execution
1	Basic option code configuration
S1	Style code 1 hardware revision

Hardware Specifications

Parameter	Specification
Model	ALR121-S51 S1
Brand	Yokogawa
Origin	Japan
Weight	0.34 kg
Dimensions	100 mm x 80 mm x 30 mm
Operating Temp	-40 to +75 deg C
Power Consumption	0.5 A at 24 VDC
Interface Ports	2 ports (RS-422/RS-485 4-wire system)
Communication Mode	Half-duplex, Start-stop synchronization
Transmission Speed	1200 / 2400 / 4800 / 9600 / 19200 / 38400 bps
Transmission Distance	Up to 1200 m (RS-485), 15 m (RS-422)
Isolation Voltage	2000 VAC for 1 min
Mounting Compatibility	AFV30, AFV40, ANB10, ANB11 nodes

4-20 mA HART Loop Protocol & Channel Isolation

The Yokogawa ALR121-S51 S1 serial communication module provides optical channel-to-channel isolation rated at 2000 VAC for 1 minute between field side wiring and the station backplane. This galvanic isolation suppresses common-mode noise and ground potential differences when bridging Modbus RTU devices, FA-M3 PLCs, or 4-20 mA HART multi-drop loop gateways to the Field Control Station (FCS). Differential signal transmission via 4-wire RS-422 and RS-485 networks prevents data corruption across high-density I/O racks.

Frequently Asked Questions

Q: Can the ALR121-S51 module be inserted into an active Field Control Station backplane slot during live operation?

A: Yes, the module supports hot-swapping within compatible backplane slots (such as ANB10 or ANB11), provided system software node configuration procedures are strictly observed.

Q: What transmission protocol codes are supported across the two independent serial ports?

A: The module supports both ASCII and Binary transmission codes with configurable 7 or 8 bit data character lengths, odd/even/no parity, and 1 or 2 stop bits.

Q: Is termination resistance required for RS-485 multipoint bus topology setups?

A: Yes, terminal resistors must be engaged at both physical ends of the RS-485 bus network line to match the 100-ohm line impedance and eliminate signal reflections.

Field Installation Guidelines

Engineers must follow established installation guidelines when wiring serial subsystem interfaces:

Insert the module into an open I/O slot of an AFV30, AFV40, ANB10, or ANB11 base unit and tighten the module securing screws.
Route shielded twisted-pair cables (such as AKB131 through AKB134) separately from high-voltage AC cables to reduce inductive noise coupling.
Connect cable shield drain wires directly to the system protective earth (PE) ground terminal at a single point.
Verify baud rate, parity bits, and station address parameters in software to match connected Modbus or subsystem hardware before putting the link online.

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