NFLR121-S00

The Yokogawa NFLR121-S00 is a two-port RS-422/RS-485 serial communication module designed for Yokogawa FCN autonomous controllers in the STARDOM platform. It provides serial data exchange with external devices such as PLCs through multipoint communication connections. Each port supports communication speeds up to 115.2 kbps, with configurable serial transmission parameters for connecting different equipment.

Communication Functions

The NFLR121 provides two RS-422/RS-485 communication ports for exchanging data between the FCN controller and external serial devices.

• Interface: RS-422/RS-485, two ports.
• Connection method: Multipoint.
• Communication speed: 300 bps to 115.2 kbps.
• Transmission code: ASCII or binary.
• Character length: 7 or 8 bits.
• Stop bits: 1 or 2 bits.
• Parity: None, even, or odd.

The module uses asynchronous start-stop synchronization. Its configurable transmission parameters allow the controller to communicate with devices using different serial communication settings.

Wiring and Communication Conditions

Both ports use terminal-block connections secured by M4 screws, with five terminals per port. The specified maximum transmission distance is 1,200 m total extended length. Two 120 ohm terminating resistors are supplied for the RS-422/RS-485 communication connections.

When using a two-wire RS-485 connection, communication is limited to half-duplex operation. Four-wire configurations can support full-duplex communication, subject to the connected equipment and communication configuration.

Model and Ordering Information

The NFLR121-S00 ordering code identifies the standard-type, basic configuration without explosion protection. Yokogawa's model and suffix documentation distinguishes the explosion-protection and ISA Standard G3 options, so the complete suffix should be checked when selecting a replacement.

Technical Specifications

Parameter	Specification
Model	NFLR121-S00
Brand	Yokogawa
Product Type	Serial Communication Module
Interface	RS-422 / RS-485
Number of Ports	2
Connection Type	Multipoint
Communication Speed	0.3 to 115.2 kbps
Synchronization	Start-stop
Transmission Code	ASCII / Binary
Character Length	7 / 8 bits
Stop Bits	1 / 2 bits
Parity	None / Even / Odd
Maximum Transmission Distance	1,200 m (total extended length)
Connector	M4 screw terminal block, 5 terminals x 2
Terminating Resistors	2 x 120 ohm
Current Consumption	500 mA at 5 VDC
Weight	0.3 kg

Frequently Asked Questions

Q: What is the difference between NFLR121 and NFLR111?

A: The NFLR121 provides two RS-422/RS-485 ports for multipoint communication, whereas the NFLR111 provides two RS-232-C ports for point-to-point communication. The interface type and wiring requirements must match the connected equipment.

Q: Can the NFLR121-S00 communicate with Modbus devices?

A: Yes. Yokogawa documents an FCN application using the NFLR121 for Modbus RTU master and slave communication. The required port configuration and application logic must be implemented in the controller engineering environment.

Q: Is the NFLR121 suitable for two-wire RS-485 communication?

A: Yes. Two-wire RS-485 is supported, but operation is limited to half-duplex. Four-wire connections can be used where full-duplex communication is required.

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