NFAI543-S51

The Yokogawa NFAI543-S51 is an analog output module in the Yokogawa STARDOM FCN/FCJ controller I/O family. It provides 16 isolated current-output channels with a 4-20 mA signal range for transmitting controller output commands to field devices. The module supports analog control signals where individual channel output behavior and electrical isolation are required.

Output Function and Channel Configuration

The NFAI543 provides 16 analog current-output channels. Each channel converts a controller-generated output value into a 4-20 mA current signal for an external field circuit.

Typical signal destinations include control valve positioners, current-operated actuators, and other equipment configured to accept 4-20 mA commands. The isolated output design provides electrical separation between the output circuits and the system.

Output Performance

The documented output accuracy is +/- 0.3% of full scale, with a 10 ms data refresh cycle and a 100 ms output step response time. These specifications describe the module's output update and response characteristics; they should not be interpreted as the response time of the complete field control loop.

The module also supports configurable output fallback behavior. HOLD retains the existing output value, while SETV applies a specified output value when fallback is detected. Fallback settings can be configured for individual channels.

Electrical Isolation and System Interface

The module provides a withstand voltage of 1500 V AC between the output circuits and the system. This isolation specification defines the electrical separation between the field-side output and the controller system; it does not indicate independent isolation between all 16 output channels.

The NFAI543 is listed in Yokogawa's STARDOM FCN I/O documentation. Its documented interface options include pressure-clamp terminal blocks and 40-pin MIL connector connections. The selected terminal arrangement must match the installed wiring hardware.

Output Fallback and Maintenance

The output fallback function allows each channel to retain its configured behavior when a fallback condition occurs:

• HOLD: Retains the existing output value.
• SETV: Outputs a predefined value.

The FCN-500 Technical Guide identifies the NFAI543 as a hot-swappable I/O module. Replacement procedures must still follow the applicable controller configuration and system maintenance requirements.

Technical Specifications

Parameter	Specification
Model	NFAI543-S51
Brand	Yokogawa
Product Type	Analog Output Module
Product Family	STARDOM FCN/FCJ
Output Channels	16
Output Signal	4-20 mA
Channel Isolation	Isolated
Withstand Voltage	1500 V AC (output to system)
Output Accuracy	+/- 0.3% of full scale
Data Refresh Cycle	10 ms
Output Step Response Time	100 ms
Temperature Drift	+/- 0.01% of full scale per deg C (maximum)
Output Fallback	HOLD / SETV, configurable per channel
Hot Swap	Supported
Terminal Options	Pressure-clamp terminal block / 40-pin MIL connector

Frequently Asked Questions

Q: Can the NFAI543-S51 be replaced without rewiring the field connections?

A: The FCN platform supports replacement of hot-swappable I/O modules without rewiring. The replacement must have a matching terminal arrangement and compatible system configuration.

Q: What is the difference between the NFAI543 and NFAV544?

A: Both are 16-channel isolated analog output modules. The NFAI543 provides 4-20 mA current outputs, whereas the NFAV544 provides -10 to +10 V voltage outputs. They are not direct signal-type substitutes.

Q: What output behavior is available during a fallback condition?

A: The module supports HOLD and SETV. HOLD retains the existing output, while SETV applies a configured output value. The fallback behavior can be configured separately for each channel.

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