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ALR121-S00 S1

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The Yokogawa ALR121-S00 S1 is a serial communication module with RS-422/RS-485 interface, supporting Modbus slave and subsystem communication for safety control systems.
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Technical specifications for ALR121-S00 S1

  • Manufacturer:
    Yokogawa
  • Part Number:
    ALR121-S00 S1
  • Product Family:
    Centum CS-Centum VP
  • Product Type:
    Communication Module
  • Stock:
    1
  • Transmission Speed:
    1200/2400/4800/9600/19200/38400 bps
  • Character Length:
    8 bits (fixed)
  • Stop Bit Length:
    1/2 bits
  • Lag Time:
    1 ms
  • Transmission Distance:
    Max. 1200 m (total extended length)
  • Current Consumption:
    0.5 A
  • Weight:
    0.3 kg
  • Estimated shipping dimensions:
    3.2x14.3x13cm
  • Tariff Code:
    8517795000
  • Country of origin:
    Japan
  • Place of shipment:
    Xiamen, Fujian, China
By purchasing this item, you agree to the Terms & Conditions, ApterPower is not an authorized distributor for listed manufacturers or tradenames and therefore the manufacturer's warranty does not apply. All our products come with ApterPower's 1-year warranty.

More Information

Overview Manuals Specifications Application Communication Safety & Compliance

Features:

  • Supports point-to-point and multipoint connections over 1200 meters.
  • Enables data exchange with external Modbus masters and sequencers.
  • No interference with safety loops in Yokogawa safety control systems.
The ALR121-S00 S1 features an RS-422/RS-485 (4-wire system) interface that supports both point-to-point (RS-422) and multipoint (RS-485) connection methods. This flexibility allows the ALR121-S00 S1 to communicate with a single device in RS-422 mode or with multiple devices in RS-485 mode. With transmission speeds from 1200 to 38400 bps and a maximum transmission distance of 1200 meters, the ALR121-S00 S1 is suitable for large-scale industrial installations. The half-duplex communication and start-stop synchronization ensure reliable data transfer.

The ALR121-S00 S1 provides both Modbus slave communication and subsystem communication functions. The Modbus slave function allows external Modbus master systems to access SCS data, enabling integration with separate systems. The subsystem communication function enables data exchange with sequencers and other devices. The ALR121-S00 S1 uses binary transmission code with 8-bit character length, 1/2 stop bits, and none/even/odd parity options. The 1 ms lag time after data transmission ensures proper timing.

The ALR121-S00 S1 is an interference-free module that has no interference with the safety loop, ensuring the integrity of safety functions. It mounts on SSC60□, SSC50□, SSC57□, SSC10□ safety control units, and SNB10D safety node units connected via ESB bus. The ALR121-S00 S1 runs on CFS1300 (SSC60□), CFS1100 (SSC50□/SSC10□), and CFS1170 (SSC57□) control functions. Engineering work is performed with CHS5100 Safety System Generation and Maintenance Function Package.

The ALR121-S00 S1 YOKOGAWA Communication Module may still be available for purchase and support from Apter Power beyond End-Of-Life (EOL) by the manufacturer (OEM).

YOKOGAWA ALR121-S00 S1 Communication Module Manuals, Datasheets, Drivers, Link Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description. All prices are shown in USD.
YOKOGAWA ALR121-S00 S1 Communication Module Specs

General

  • Manufacturer YOKOGAWA
  • Model ALR121-S00 S1
  • Condition New Original ready stock
  • Product Family ALR121-S51 S1,ALR121-S50 S1,ALR121-S50,ALR121-S51
Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description. All prices are shown in USD.
  • Subsystem Integration: Connects the main DCS directly to auxiliary package systems, such as Programmable Logic Controllers (PLCs) managing packaging lines, water treatment skids, or compressor controls.
  • Specialized Analytical Monitoring: Links to plant analyzer equipment, including gas chromatographs, continuous emissions monitoring systems (CEMS), and custody transfer flow meters.
  • Emergency Systems Readout: Monitors status tags from independent emergency shutdown systems (ESD) or fire & gas (F&G) logic solvers for display on the main operator console.
  • Physical Interface Ports: Features two independent serial ports configured for RS-422 (4-wire) or RS-485 (2-wire) physical layer standards. Communication lines are wired using dedicated D-sub or terminal block adapter assemblies.
  • Protocol Support: Supports industry-standard Modbus RTU (Master/Slave) and ASCII protocols right out of the box, handling multi-node arrangements with up to 31 downstream slave devices per port.
  • Baud Rates and Distances: Handles standard transmission velocities ranging from 1200 bps up to 38400 bps, covering physical cable loop lengths of up to 1200 meters over high-quality shielded twisted-pair (STP) lines.
  • Port-to-Port Galvanic Isolation: Each communication port is built with heavy internal optocouplers and electrical isolation barriers. This stops physical field electrical surges, ground loops, or high lightning-induced transient voltages from burning out the card or traveling back into the main DCS CPU backplane.
  • Electromagnetic Compatibility (EMC): Complies with CE marking and C-Tick rules for noise immunity. It ignores heavy electromagnetic emissions from surrounding large motors or switchgears and emits zero interference into adjacent DCS processing loops.
  • Hazardous Location Certifications: Satisfies FM (Factory Mutual), CSA, and ATEX/IECEx Zone 2 / Class I, Div 2 compliance requirements, certifying it for safe placement inside sealed industrial enclosures close to hazardous processing sections.
Description
The Yokogawa ALR121-S00 S1 is a serial communication module designed for Yokogawa safety control systems (SCS). This module enables Modbus slave communication, allowing data in SCS to be accessed by external Modbus master systems. The ALR121-S00 S1 also supports subsystem communication for data exchange with sequencers and other devices.

The Yokogawa ALR121-S00 S1 features an RS-422/RS-485 (4-wire system) interface supporting both point-to-point (RS-422) and multipoint (RS-485) connections. The ALR121-S00 S1 offers transmission speeds from 1200 to 38400 bps and a maximum transmission distance of 1200 meters. The ALR121-S00 S1 uses start-stop synchronization with half-duplex communication.


The ALR121-S00 S1 features two ports with D-sub-9-pin female connectors and terminal block connections with M4 screws (5 poles x 2 ports). The Yokogawa ALR121-S00 S1 is an interference-free module that has no interference with the safety loop. The ALR121-S00 S1 supports both Modbus slave communication and subsystem communication functions. Engineering work uses CHS5100 Safety System Generation and Maintenance Function Package.
Alternative Names
ALR121-SOO S1 ALRI2I-S00 SI ALR121 S00 S1 ALR121-S50 ALR121-S51 ALR121-S51 S1 ALR121-S50 S1 ALF111-S00 S1
Technical notes
The Yokogawa ALR121-S00 S1 is an RS-422/RS-485 serial communication module for safety control systems. It supports Modbus slave and subsystem communication at speeds up to 38400 bps over 1200 m. Features half-duplex start-stop synchronization, 8-bit data, and 0.5 A consumption. Interference-free design ensures safety loop integrity.
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FAQS

The following is a list of questions commonly asked by our customers. Please contact us if you have a question about our process that is not answered below.
What is the primary function of the ALR121-S00 S1?
It provides Modbus slave communication and subsystem communication for Yokogawa safety control systems via RS-422/RS-485.
What are the key specifications of the ALR121-S00 S1?
It supports up to 38400 bps, 1200 m transmission distance, 0.5 A consumption.
Is the ALR121-S00 S1 interference-free for safety loops?
Yes, the ALR121-S00 S1 is an interference-free module with no interference with the safety loop.

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