Description

Yokogawa AFG84D-H4123 Field Control Unit

Configured for deterministic execution of regulatory control loops in the CENTUM VP Distributed Control System, the Yokogawa AFG84D-H4123 (base model AFG84D Field Control Unit) provides direct physical and electrical interfacing between field instrumentation and the Vnet/IP control network.

Suffix Breakdown & Model Matrix

Code	Definition
AFG84	Base Field Control Unit (Duplex)
D	Dual-redundant Processor/Power configuration
H41	Hardware revision denoting 220-240 VAC power input and G3 conformal coating
23	Factory-specific firmware revision and terminal block configuration

Hardware Specifications

Parameter	Specification
Brand	Yokogawa
Origin	Japan
Weight	18 kg
Dimensions	482.6 mm x 310 mm x 265 mm (19-inch rack)
Operating Temp	0 to 50 degC
Power Consumption	250 VA (typical load)
Power Supply	220-240 VAC, 50/60 Hz
Redundancy	Duplex (CPU, Power, Bus)
Network Interface	Vnet/IP, ER Bus

4-20 mA HART Loop Protocol Handling

The unit processes analog input signals via local FIO modules supporting 4-20 mA HART protocol. Channel-to-channel isolation is maintained at 500 VDC minimum. The backplane logic enforces HART burst mode timing constraints to prevent data collision on shared multidrop networks. Signal conversion latency from field termination to Vnet/IP packet transmission is fixed at 50 ms.

Frequently Asked Questions

Q: What is the maximum hot-swap current limit for replacing a power supply module while the unit is energized?

A: The redundant power supply supports hot-swapping with a maximum inrush current of 30 A for 50 ms. Ensure the replacement module matches the voltage rating of the active supply.

Q: Does the AFG84D-H4123 support automatic firmware rollback during a failed update?

A: No. Firmware flashing requires manual verification of the .bin file checksum via the engineering station. Failed updates require physical access to the maintenance port for recovery.

Q: What is the switching delay during a CPU failover event?

A: The duplex configuration ensures control output continuity with a switchover time of less than 10 ms. No output hold timers are required.

Field Installation Guidelines

Install the unit in a 19-inch rack with a minimum clearance of 150 mm at the rear for bus cable routing. Terminate shield drains directly to the chassis ground terminal using a 5/16 inch ring terminal; do not connect shields at the field instrument end to avoid ground loops. Torque all power terminals to 1.2 Nm. Verify the ER Bus termination resistors are set to ON for the final node in the chain.

Specifications

• Brand: Yokogawa

Advantages

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