Yokogawa ALR121-S50 ALR121 Serial Communication Module

Hardware Specifications

Serial Communication and DCS Interface Characteristics

The ALR121-S50 handles serial data transmission through RS-422 and RS-485 electrical interfaces. Its two communication ports support connection configurations according to the selected interface.

• RS-422: Supports point-to-point serial communication.
• RS-485: Supports multipoint communication over a shared serial network.
• Half-duplex operation: Controls data transmission in alternating directions rather than simultaneous bidirectional transmission.
• Start-stop synchronization: Uses start and stop signaling to frame transmitted data.
• Transmission formats: Supports ASCII and binary transmission codes.
• Selectable baud rates: Provides six specified transmission speeds from 1200 bps to 38400 bps.

For process-control integration, configure the communication parameters consistently between the ALR121-S50 and the connected serial equipment. In addition, verify the selected interface, transmission speed, data format, and network topology before commissioning.

Frequently Asked Questions

Q: What communication interfaces does the Yokogawa ALR121-S50 support?

A: The ALR121-S50 supports RS-422 and RS-485 interfaces. RS-422 provides point-to-point communication, while RS-485 supports multipoint connections.

Q: What transmission speeds and data formats are available?

A: The module supports 1200, 2400, 4800, 9600, 19200, and 38400 bps. It also supports ASCII and binary transmission codes.

Q: What is the current consumption of the ALR121-S50?

A: The specified current consumption is 0.5 A. Check the applicable system power budget before installing the module.

Field Installation Guidelines

1. Verify the complete module designation, ALR121-S50, against the system hardware configuration.
2. Confirm that the receiving equipment supports the selected RS-422 or RS-485 interface.
3. Select the appropriate point-to-point or multipoint wiring topology before connecting field communication cables.
4. Configure matching transmission speeds and data formats at both communication endpoints.
5. Route serial communication cables separately from high-voltage power conductors and sources of electrical interference.
6. Apply appropriate cable shielding and grounding practices according to the system installation documentation.
7. Confirm the available power supply capacity against the module’s specified 0.5 A current consumption.
8. Inspect terminal connections and cable continuity before applying power.
9. Verify communication status and data exchange after installation.