Product Core Brief
- Model: YOKOGAWA ALR121-S00
- Brand: YOKOGAWA
- Series: CENTUM CS 3000 Communication Module
- Core Function: 2-port RS-422/RS-485 serial communication module for connecting external PLCs, instruments, and Modbus-RTU devices to CENTUM CS 3000 DCS.
- Product Type: DCS Serial Communication Module
- Key Specs: 2 ports | RS-422/RS-485 | 1,200–115.2 kbps | Modbus-RTU support | standard type, no explosion protection, basic option
- Condition: New Original (New Surplus) / Factory Sealed
Product Introduction
A lost serial link to a third-party PLC or analyzer can blind a DCS to critical data. The YOKOGAWA ALR121-S00 is a 2-port RS-422/RS-485 serial communication module for CENTUM CS 3000, used to integrate external devices — PLCs, analyzers, flow computers, weigh scales, and Modbus-RTU instruments — into the DCS.
The suffix structure follows Yokogawa convention: “-S” = standard type, “5” = no explosion protection, “0” = basic option, giving ALR121-S50 / ALR121-S51 variants under the ALR121 family. In practice, ALR121-S00 is commonly referenced as the ALR121 RS-422/RS-485 communication module, with the exact suffix confirmed from the label. It supports baud rates from 1,200 to 115.2 kbps and is widely deployed as a Modbus-RTU master interface in CS 3000 systems.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Model | AWA |
| Product Type | Serial Communication Module |
| Compatible System | CENTUM CS 3000 |
| Interface | RS-422 / RS-485, 2 ports |
| Baud Rate | 1,200 – 115,200 bps |
| Protocol Support | Modbus-RTU (with Yokogawa communication software package) |
| Suffix Meaning | -S standard / 5 no explosion protection / 0 basic option |
| Typical Application | PLC integration, instrument communication, Modbus-RTU master |
Key Selling Points & Differentiators
- 2-port RS-422/RS-485 interface for third-party device integration.
- Modbus-RTU master capability for connecting PLCs, analyzers, and field instruments.
- Direct replacement for existing ALR121 slots when suffix and firmware match.
- Factory-sealed surplus inventory with visual QA and 12-month warranty.
- Not a process I/O card; it is a serial communication module.
Quality Transparency SOP
- Visual inspection: Verify label “ALR121-S00,” connector pins, and housing condition.
- Seal verification: Confirm original anti-static bag, desiccant, and factory labeling.
- Suffix cross-check: Match the suffix code with the replaced module (S50, S51, SE0, SE1).
- Slot verification: Confirm installation in the correct communication slot, not a standard I/O slot.
- Communication test: Verify baud rate, parity, and Modbus-RTU addressing after installation.
- Link check: Inspect RS-485 cabling, termination resistors, and shield grounding.
Technical Risk Avoidance
❗ Confirm the exact suffix. ALR121-S00 is a reference designation; the installed module may be ALR121-S50, ALR121-S51, ALR121-SE0, or ALR121-SE1.
❗ This is a communication module, not a process I/O card. Do not substitute it for ADV, AAI, AAT, or AAR modules.
❗ Verify Modbus-RTU licensing. Full Modbus master functionality typically requires the Yokogawa communication software package.
❗ Check RS-485 polarity and termination. Mismatched A/B wiring or missing termination can cause communication errors.
❗ ALR121 is for CS 3000; CENTUM VP systems may use different communication modules. Confirm system compatibility.
Buyer’s FAQ
Is the YOKOGAWA ALR121-S00 a genuine OEM part?
Yes. It is supplied as an original Yokogawa ALR121-series communication module, typically as new surplus or factory sealed.
Whatthe do?
It provides 2-port RS-422/RS-485 serial communication for CENTUM CS 3000, commonly used for Modbus-RTU integration with PLCs and instruments.
Can it replace -S50 or -S51?
Functionally yes, as they belong to the same ALR121 RS-422/RS-485 family, but the exact suffix should be confirmed against the replaced module.
Does it support Modbus-RTU?
Yes, with the appropriate Yokogawa communication software package, it can operate as a Modbus-RTU master.
What warranty do you offer?
A 12-month warranty against manufacturing defects and DOA issues. Damage from incorrect wiring, wrong baud rate, missing software license, or incompatible system is not covered.
