Description

Yokogawa NFAF135-S50 Output Frequency Module

Configured for frequency pulse output generation in CENTUM VP and ProSafe-RS I/O architectures, the Yokogawa NFAF135-S50 (NFAF135-S50 Output Frequency Module) provides direct physical/electrical execution for digital frequency-based signal delivery within distributed control system I/O nodes.

The module operates as a pulse and frequency output interface used to drive downstream instrumentation or process counters through isolated switching stages. Signal generation is implemented via internal timing logic synchronized to the host backplane, supporting deterministic output behavior under system scan control. Electrical separation between field terminals and internal logic is implemented through galvanic isolation barriers. The S50 suffix indicates a standardized hardware revision with environmental protection treatment and defined terminal interface configuration within Yokogawa I/O assembly families.

Suffix Breakdown & Model Matrix

No official public decomposition of internal model subfields for NFAF135-S50 is provided in the supplied technical data. The suffix "-S50" is treated as a manufacturing and configuration identifier indicating a specific hardware revision and protection/assembly variant within the same base module family.

Hardware Specifications

Parameter	Specification
ModelBrand	Yokogawa NFAF135-S50
OperatingTemp	-20 degC to 70 degC
PowerConsumption	< 350 mA at 5 VDC internal supply
Module Type	Output Frequency / Pulse Output Module
Channels	Typically 4 or 8 channels (system dependent)
Output Range	Frequency / pulse output, approx 0.1 Hz to 10 kHz (application dependent)
Accuracy	plus/minus 0.05 % full scale
Isolation	Galvanic isolation between field and logic circuits
Response Time	< 10 ms to 40 ms (system dependent scan cycle)

DCS I/O Signal Architecture Characteristics (Yokogawa)

The module is integrated into Yokogawa distributed control environments where backplane-based deterministic scheduling governs output refresh cycles. In mixed I/O nodes, channel-to-channel isolation structures reduce cross-coupling between adjacent frequency outputs. Within Yokogawa architectures, I/O segmentation may coexist with analog 4-20 mA HART loops and FOUNDATION Fieldbus segments, although this module itself is dedicated to discrete frequency generation rather than analog transmission. Internal timing alignment is derived from system scan synchronization rather than autonomous oscillator free-run control.

Frequently Asked Questions

Q: Can the NFAF135-S50 be hot-swapped during system operation?
A: Hot-swap capability depends on the I/O base unit and system configuration. Electrical backplane isolation must be maintained before insertion or removal to prevent transient bus disturbance.

Q: Does each channel operate with independent timing?
A: Channel execution is generally synchronized to the system scan cycle. Independent asynchronous timing is not typically implemented at channel level.

Q: What limits the maximum output frequency stability?
A: Stability is governed by backplane scan resolution, internal timing clock distribution, and load characteristics on the output stage.

Field Installation Guidelines

Ensure all field wiring is terminated on the correct Yokogawa I/O terminal base assembly matching the NFAF135 series interface specification. Shielded cabling is required for frequency output lines in electrically noisy environments, with shield grounding performed at a single-point earth reference.

Do not apply field voltage to output terminals prior to verifying backplane seating integrity. Module insertion must be performed with system power removed or under validated hot-swap procedures defined by the control system rack architecture. Maintain separation between frequency output wiring and high-energy switching conductors to reduce induced noise coupling. Terminal torque and conductor preparation shall follow standard industrial control panel wiring practices.

Specifications

• Brand: Yokogawa

Advantages

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