Yokogawa ALR121-S51 CENTUM VP RS-422 / RS-485 Serial Communication Module
A CENTUM VP serial communication module for RS-422 or RS-485 subsystem links, retained under the complete S51 execution.
Technical Summary
PRODUCT CONTEXTALR121-S51 is a Yokogawa ALR121 serial communication module used by a field control station to exchange data with supported subsystems over RS-422 or RS-485. It provides two ports, and both ports use the same selected communication function.
The module supports half-duplex start-stop transmission with ASCII or binary data formats. The complete S51 code, installed node, protocol package and connected subsystem identity should stay together because the interface standard alone does not define compatibility.
Specifications
CONTROLLED DATARS-422 or RS-485
2
RS-422 point-to-point; RS-485 multipoint
Half-duplex, start-stop
1200 to 38,400 bit/s, function dependent
ASCII or binary
7 or 8
1 or 2
None, even or odd
1200 m
M4 screw terminal, 5 poles × 2
Features
FUNCTIONAL DISTINCTIONSProtocol-based subsystem access
Supports Yokogawa serial communication packages for approved external subsystems.
Flexible physical layer
The installed design can use RS-422 point-to-point or RS-485 multipoint wiring.
Two coordinated ports
Both ports share the selected communication function, simplifying a controlled module record.
Long-distance serial link
Published cable length reaches 1200 m when the approved wiring conditions are met.
Compatibility
SELECTION BOUNDARIESCommunication package
Match the selected Yokogawa serial function and the connected subsystem protocol.
Electrical network
Confirm RS-422 or RS-485 topology, termination, biasing, shielding and station count.
Node platform
Verify the supported FCS or ESB node unit and the installed module position.
Replacement
SERVICE WORKFLOWDocument
Record ALR121-S51, node slot, protocol function, every station address and both port cable routes.
Install
Preserve terminal assignments, shield treatment and network termination while following the approved node procedure.
Test
Confirm communication status and read/write behavior for every configured subsystem station.
FAQ
CUSTOMER DECISION SUPPORTCan the two ALR121-S51 ports run different communication functions?
Yokogawa specifies that both ports use the same communication function.
What network record is needed for ALR121-S51?
Provide the RS-422/RS-485 topology, cable length, termination, baud rate, frame format and all station addresses.
Does the ALR121 interface alone prove protocol compatibility?
No. The configured Yokogawa communication package and connected subsystem must also be supported.
What should be checked on a long ALR121-S51 link?
Review cable type, total length, shielding, grounding, termination and the RS-485 station count.
How is ALR121-S51 accepted after replacement?
Verify healthy module status and successful read/write exchanges with each configured subsystem.
About IndustryParts
https://www.industryparts.com/Controlled handling for ALR121-S51
IndustryParts keeps the submitted ALR121-S51 identity, requested quantity and installed-system evidence together so a proposed supply can be checked before dispatch.
- Complete submitted model retained
- Installed-system evidence reviewed
- Quotation record kept with the enquiry
