YOKOGAWA LC81*B Communication Modules

The YOKOGAWA LC81*B, also cataloged as the LC81 Communication Modules, operates as a dedicated hardware component for high-speed deterministic bus data exchange within Field Control Unit (FCU) architectures. It handles physical layer frame processing and control signaling over the proprietary RL-BUS network to maintain continuous telemetry between central processing units and field-level subnodes.

Hardware Specifications

4-20 mA HART Loop Protocol & Fieldbus Connectivity

The YOKOGAWA LC81*B interface card processes digital communication frames across the system backplane to integrate subsystem field telemetry with higher-level DCS controllers. While handling high-speed packet transfer on the primary RL-BUS line, the module supports downstream digital fieldbus pass-through and 4-20 mA HART loop protocol routing. Furthermore, internal signal conditioning circuitry suppresses common-mode electromagnetic noise, preventing field-line harmonic interference from degrading high-speed control loops or corrupting process variable telemetry.

Frequently Asked Questions

Q: What precautions are necessary regarding power distribution when installing the LC81*B card into a backplane slot?

A: Installers must power down the target rack segment or strictly follow Yokogawa hot-swap protocols to prevent voltage transients on the shared system bus. In addition, verify that the 3 W power draw does not exceed the remaining backplane power supply budget.

Q: How does the module handle high-frequency communication noise on the RL-BUS physical interface?

A: Integrated transformer coupling and isolated bus transceiver circuitry attenuate high-frequency noise and ground loops across the communication lines.

Field Installation Guidelines

Mount the YOKOGAWA LC81*B card directly into the designated FCU card slot, ensuring the rear connector seats firmly into the backplane. Route all external RL-BUS communication cabling through shielded twisted-pair (STP) lines kept physically separated from high-voltage AC power conductors. Terminate the cable shield at a single-point instrument ground (IG) terminal to prevent ground loop current flow. Finally, torque all terminal retaining screws to manufacturer specifications before energizing the control rack.