Description

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 RS-422/RS-485 serial data exchange within Yokogawa STARDOM and CENTUM VP control systems.

HardwareSpecifications

Parameter	Specification
ModelBrand	Yokogawa NFLR121-S50
Origin	Japan
Weight	0.3 kg (Net), ~1.0 kg (Shipping)
Dimensions	Standard STARDOM modular form factor
OperatingTemp	-10 degC to +55 degC
StorageTemp	-25 degC to +70 degC
Humidity	5% to 95% RH, non-condensing
PowerConsumption	500 mA Max
InterfaceType	RS-422 / RS-485, 2 Ports
Topology	Point-to-Point (RS-422), Multipoint (RS-485)
CommunicationMode	Half-duplex / Full-duplex (2-wire systems only Half-duplex)
Synchronization	Start-stop
TransmissionCode	ASCII / Binary
CharacterLength	7 or 8 bits
StopBits	1 or 2 bits
ParityCheck	None / Even / Odd
MaxTransmissionDistance	Up to 1,200 meters
Connection	5-pole terminal block ×2, M4 screws, built-in/external 120-ohm termination resistors

Process Control Specific Features

• Supports channel-to-channel isolation between serial ports to prevent electrical interference.
• Compatible with Modbus RTU/ASCII devices for master/slave integration.
• Diagnostic LEDs indicate TX and RX activity on each port.
• Suitable for interfacing with FOUNDATION Fieldbus and Profibus PA devices via gateway controllers.
• Cold junction compensation (CJC) is implemented in signal processing to stabilize measurement across temperature variations.

Frequently Asked Questions

Q: Can the NFLR121-S50 module operate in hot-swap conditions?
A: The module does not support live hot-swapping; power must be removed from the rack before insertion or removal.

Q: Are the built-in termination resistors configurable?
A: Yes, each RS-485 port includes a switchable 120-ohm resistor for line termination based on network topology.

Q: What is the maximum allowed cable length for RS-485 communication?
A: Up to 1,200 meters total, including all branches and spurs, with proper twisted-pair wiring and termination.

Field Installation Guidelines

• Mount module in STARDOM/FCN rack using standard slots; ensure firm mechanical engagement.
• Connect RS-422/RS-485 signals with twisted pair shielded cables; terminate shields at one end only to prevent ground loops.
• Maintain separation from high-voltage power cables to reduce electromagnetic interference.
• Observe polarity for TX+/TX- and RX+/RX- lines; improper wiring may damage ports.
• Verify diagnostic LEDs for transmission and reception activity after installation before starting normal operation.

Specifications

• Brand: Yokogawa

Advantages

• High reliability in industrial environments
• Supports continuous operation
• Compatible with major PLC/DCS systems