Yokogawa NFLR121-S50 Serial Communication Module

The Yokogawa NFLR121-S50, also cataloged as the NFLR121 Serial Communication Module, operates as a dedicated hardware component for serial data exchange and protocol conversion within STARDOM modular controller systems.

Hardware Specifications

4-20 mA HART Loop Protocol and Channel Isolation

The serial interface circuitry maintains high channel-to-channel isolation and differential line driving to protect backplane logic from ground potential variations across long-distance field buses. Signal lines (TX+, TX-, RX+, RX-) utilize balanced transmission mode to suppress common-mode electromagnetic noise during high-speed Modbus frame exchanges. Integrated noise filtering and galvanic isolation guard subsystem networks against high-voltage industrial field surges.

Frequently Asked Questions

Q: What transmission distance is supported when using the AKB161 cable with the NFLR121-S50?

A: The AKB161 compatible cable supports serial communication distances up to 100 m when connecting to FA500 subsystems over RS-422/RS-485 interfaces.

Q: How should the signal ground (SG) terminal be wired in multipoint RS-485 networks?

A: The SG terminal must be interconnected across all serial nodes to establish a common reference potential, preventing common-mode voltage limits from being exceeded while keeping the cable shield grounded at a single point.

Field Installation Guidelines

1. Ensure the controller rack power supply is switched off before inserting or removing the NFLR121-S50 module from the baseplate slot.
2. Terminate the RS-422/RS-485 differential signal lines (TX/RX) using external terminating resistors at both physical ends of a multipoint network trunk.
3. Wire the TX+, TX-, RX+, RX-, and SG terminals strictly according to the terminal symbol mapping to prevent signal phase reversal.
4. Route serial communication cables away from high-voltage power lines and motor drives to minimize inductive noise coupling.