Description

Yokogawa AFS20D Duplexed Field Control Unit

The Yokogawa AFS20D, also cataloged as the AFS20D Duplexed Field Control Unit, operates as a dedicated hardware component for executing continuous and sequence control within CENTUM VP and CENTUM CS 3000 platforms. It features redundant processors, power modules, and communication buses to maintain uninterrupted process control under hardware faults.

Hardware Specifications

Parameter	Specification
ModelBrand	Yokogawa AFS20D
Origin	Japan
Weight	Approx. 250 kg (base cabinet), 400 kg (fully loaded)
Dimensions	Cabinet-integrated, standard rack installation
OperatingTemp	0 to 55 degC
PowerConsumption	100–120 V AC: 1700 VA 220–240 V AC: 2000 VA 24 V DC: 50 A
Processor	VR5432 RISC Processor, 133 MHz
MainMemory	16 Mbyte, battery-backed (max. 72 h)
FCUStatusOutput	3 terminals (NC, NO, C), 250 V AC/30 V DC max. ratings
Communication	Dual-redundant V net, dual-redundant RIO bus
Mounting	Integrated cabinet, M6 power terminals, M8 grounding, M4 contact terminals

DCS-Specific Connectivity Features

The AFS20D supports direct process control interfacing with 4-20 mA HART loops and maintains channel-to-channel isolation to minimize signal interference. Remote I/O modules communicate over dual-redundant RIO buses, and cold junction compensation (CJc) is implemented for accurate thermocouple readings. FOUNDATION Fieldbus and Profibus PA networks can be connected through dedicated interface modules, ensuring deterministic loop updates and fault-tolerant data transfer.

Frequently Asked Questions

Q: VnA: Can the AFS20D modules be hot-swapped during operation?
A: Hot-swapping is not supported for processor modules; only certain peripheral I/O cards with independent power may be replaced without shutdown.

Q: VnA: What is the maximum failover time between redundant processors?
A: Redundancy switchover is hardware-controlled and typically completes within a few milliseconds, ensuring no disruption of process signals.

Q: VnA: Are firmware updates compatible across all AFS20D revisions?
A: Firmware compatibility depends on memory size and bus configuration; updates must be verified against the specific hardware revision matrix.

Field Installation Guidelines

1. Position the cabinet on a level surface with adequate ventilation clearance on all sides.
2. Connect AC or DC power through M6 screw terminals; verify correct polarity and voltage rating.
3. Ground the cabinet using the M8 bolt terminal; ensure all connected shields of communication cables terminate at ground to reduce EMI.
4. Route V net and RIO cables separately from high-power lines to prevent crosstalk.
5. Install FCU contact output wiring with M4 terminals, ensuring no mechanical stress on screw connections.
6. Avoid direct exposure to vibration or condensation; ambient temperature should remain within 0–55 degC.

Specifications

• Brand: Yokogawa

Advantages

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