Yokogawa ALR121-S00 S1 Serial Communication Module

Hardware Specifications

Yokogawa DCS Serial Communication Interface Characteristics

The ALR121-S00 S1 provides RS-422/RS-485 serial communication channels for exchanging data between CENTUM VP/CS 3000 Field Control Stations and external subsystems. Moreover, the module supports half-duplex communication with start-stop synchronization, allowing controlled transmission timing between connected devices.

The module uses binary transmission coding and supports configurable communication speeds from 1200 bps to 38400 bps. In addition, the RS-485 multipoint connection capability allows multiple field devices to communicate through a shared serial network, while RS-422 supports point-to-point communication arrangements.

For Yokogawa process control applications, serial communication modules commonly interface with external controllers, PLC devices, and intelligent instruments. Therefore, proper signal wiring, grounding, and communication parameter configuration are required to maintain stable data exchange.

Frequently Asked Questions

Q: What serial interfaces does the Yokogawa ALR121-S00 S1 support?
A: The module supports RS-422 and RS-485 interfaces. It provides point-to-point communication through RS-422 and multipoint communication through RS-485.

Q: What communication mode does the ALR121-S00 S1 use?
A: The module operates with half-duplex communication and uses start-stop synchronization with binary transmission coding.

Q: What is the maximum transmission distance supported by this module?
A: The ALR121-S00 S1 supports a maximum transmission distance of 1200 m under specified communication conditions.

Field Installation Guidelines

• Install the module in the designated Yokogawa FCS or compatible node unit slot according to the system hardware configuration manual.
• Verify RS-422/RS-485 wiring polarity before connecting field communication cables.
• Use shielded communication cables for serial signal wiring and connect the cable shield according to the site grounding practice.
• Separate serial communication cables from high-voltage power lines and strong electromagnetic interference sources.
• Confirm communication parameters, including baud rate, character length, and stop bit settings, before establishing communication with external devices.
• Check connector seating and module mounting condition after installation to prevent intermittent communication faults.