YOKOGAWA ALR121-S00 – S1 Serial Communication Module | CENTUM VP / CS 3000 DCS Platform
Engineering Background
The ALR121-S00 is a dedicated serial communication interface module developed by Yokogawa Electric Corporation for integration within the CENTUM VP and CS 3000 Distributed Control System (DCS) platforms. Designed to bridge legacy serial field devices with modern DCS architectures, this module enables deterministic, low-latency data exchange across RS-232C / RS-422 / RS-485 serial buses — a critical requirement in continuous process industries where communication integrity directly impacts safety and yield.
Product Positioning
Targeted at process automation engineers managing brownfield plant expansions, the ALR121-S00 eliminates the need for external protocol converters by natively embedding serial I/O capability into the CENTUM field control station (FCS) backplane. It is the preferred solution for integrating analyzers, flow computers, third-party PLCs, and HART-over-serial devices into a unified Yokogawa DCS environment.
Complete Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | ALR121-S00 |
| Module Type | S1 Serial Communication Module |
| Manufacturer | Yokogawa Electric Corporation |
| Compatible Platform | CENTUM VP, CENTUM CS 3000 |
| Serial Interfaces | RS-232C, RS-422, RS-485 |
| Communication Ports | 2 independent serial ports |
| Baud Rate Range | 300 bps – 115,200 bps |
| Data Bits | 7 or 8 bits |
| Parity | None / Even / Odd |
| Stop Bits | 1 or 2 |
| Protocol Support | Modbus RTU/ASCII, proprietary Yokogawa serial, user-defined |
| Isolation | Optical isolation between serial ports and backplane bus |
| Power Supply | Supplied via FCS backplane (no external PSU required) |
| Operating Temperature | 0 °C to +55 °C |
| Storage Temperature | -20 °C to +70 °C |
| Relative Humidity | 5% to 95% RH (non-condensing) |
| Mounting | FCS I/O nest slot (standard Yokogawa backplane) |
| Dimensions (W×H×D) | Conforms to CENTUM VP I/O module standard form factor |
| Certifications | CE, UL (per Yokogawa platform certification) |
| Firmware | Factory-loaded; field-configurable via CENTUM VP Builder |
Proven Application Environments
- Oil & Gas: Integration of gas chromatographs, flow computers (e.g., Emerson ROC, ABB XIO), and wellhead RTUs via Modbus RTU over RS-485.
- Petrochemical / Refining: Serial link to online analyzers (NIR, GC, viscometers) for real-time quality control loops within CENTUM VP FCS.
- Power Generation: Communication with turbine governor controllers and excitation systems using RS-422 full-duplex links.
- Pharmaceutical / Fine Chemical: FDA 21 CFR Part 11-compliant data acquisition from serial-output balances and reactors.
- Pulp & Paper / Mining: Brownfield retrofit — replacing standalone serial converters with native DCS-integrated ALR121 modules to reduce single points of failure.
Engineering Advantages
- Native DCS Integration: No external gateway hardware; serial data maps directly into CENTUM VP function blocks and historian tags.
- Dual-Port Architecture: Two independently configurable serial ports per module slot — maximizes I/O density in constrained cabinet space.
- Optical Isolation: Eliminates ground-loop interference common in long-cable industrial serial runs; protects FCS backplane from field-side transients.
- Flexible Protocol Engine: Supports Modbus RTU/ASCII natively; user-defined message framing available for proprietary device protocols.
- Hot-Standby Compatible: Supports redundant FCS configurations — seamless failover without serial communication interruption.
- Low Latency: Deterministic scan-cycle integration ensures serial data is available within the FCS control cycle for closed-loop applications.
System Architecture & Signal Flow
The ALR121-S00 occupies a standard I/O slot within the CENTUM VP Field Control Station (FCS) nest. Serial field devices connect to the module’s front-panel terminal block via shielded twisted-pair cable. The module’s onboard processor handles framing, error checking (CRC/LRC), and protocol translation, then passes structured data across the FCS internal bus to the CPU module. Within CENTUM VP Builder, the ALR121 appears as a standard I/O module; engineers assign serial data items to process tags using the Communication I/O (SEBOL or SFC) function blocks. Data is then available to all standard CENTUM VP applications: HIS operator stations, Exaquantum historian, and upstream MES/ERP systems via OPC-DA/UA.
Sourcing & Quality Verification
- Origin: Genuine Yokogawa OEM hardware — sourced from decommissioned plant upgrades and authorized surplus channels.
- Inspection: Each unit undergoes visual inspection (PCB, connectors, label integrity), functional power-on verification, and firmware version confirmation prior to listing.
- Condition: Tested surplus / refurbished — full functionality confirmed. Cosmetic wear consistent with controlled industrial environment use.
- Packaging: Anti-static bag + foam-lined carton; humidity indicator card included for international shipments.
- Warranty: 90-day Konmask operational warranty. Extended warranty available on request.
Procurement Process
- Step 1 – Inquiry: Submit your BOM or part number via support@konmask.com or WhatsApp +0086 19859288691 for availability confirmation and lead time.
- Step 2 – Quotation: Receive a formal quotation with unit price, quantity, shipping options (DHL / FedEx / sea freight), and payment terms within 24 hours.
- Step 3 – Order Confirmation: Purchase order accepted via T/T bank transfer, PayPal, or Shopify secure checkout.
- Step 4 – Dispatch: Orders ship within 1–3 business days from Hong Kong warehouse. Tracking number provided upon dispatch.
- Step 5 – After-Sales: Technical support available for installation, configuration, and compatibility verification with your CENTUM VP / CS 3000 system.
Technical FAQ
Q: Is the ALR121-S00 compatible with CENTUM CS 3000 as well as CENTUM VP?
A: Yes. The ALR121 series is hardware-compatible with both CENTUM CS 3000 R3 and CENTUM VP R5/R6 FCS nests. Verify your FCS nest model (AFV10D, AFV30D, etc.) for slot compatibility.
Q: Can the module handle RS-485 multi-drop networks?
A: Yes. RS-485 mode supports multi-drop topologies with up to 32 nodes per port. Termination resistors must be applied at both ends of the bus.
Q: What is the maximum cable length for RS-422/RS-485?
A: Up to 1,200 m (4,000 ft) at 100 kbps with shielded twisted-pair cable (120 Ω characteristic impedance). Reduce cable length proportionally at higher baud rates.
Q: Does the ALR121-S00 support HART protocol?
A: The ALR121 handles serial framing only; HART-over-serial requires a HART modem on the field side. For native HART, consider Yokogawa’s AAI/ADV I/O modules with HART pass-through.
Q: Can I use this module in a redundant FCS configuration?
A: Yes. The ALR121-S00 supports Yokogawa’s dual-redundant FCS architecture. Both primary and secondary CPU modules share access to the serial module; failover is transparent to field devices.
Q: What firmware version is installed?
A: Firmware version is confirmed during pre-shipment inspection and documented in the test report included with each unit. Contact us for specific version requirements.
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