ABB 6640635A1 Symphony Harmony Termination Module

The ABB 6640635A1, also cataloged as the 6640635A1 Servo Termination Unit (STU), operates as a dedicated hardware component for interfacing servo control signals between ABB Distributed Control Systems (DCS) and industrial servo actuators.

Hardware Specifications

Industrial Control & Backplane Communication Properties

As an integrated termination unit within ABB process control architectures, the 6640635A1 provides signal protection and bus interfacing:

• 4-20 mA HART Loop Protocol & Channel Isolation: Incorporates full electrical isolation across 8 to 16 servo voltage and current loops, isolating field actuator drives from backplane control logic to eliminate ground loops.
• Backplane Bus Communication Velocity: Direct connection to Symphony Harmony and INFI 90 backplane buses routes high-speed analog position commands to field actuators with sub-millisecond propagation delay.
• Firmware Flash Compatibility: Acts as a passive physical termination interface, maintaining signal alignment and hardware scaling parameters without requiring firmware updates during DCS controller upgrades.

Frequently Asked Questions

Q: Can the 6640635A1 handle both voltage and current signal formats simultaneously?

A: Yes, the unit supports termination for both voltage and current-based servo control signals across its channel inputs.

Q: What level of electrical isolation does the board provide between field drives and the DCS?

A: The STU features full electrical isolation between individual servo channels and the main DCS system bus to isolate drive-related noise.

Q: How many servo channels are available on a single termination board?

A: The board typically accommodates between 8 and 16 servo channels, depending on specific system hardware configuration.

Field Installation Guidelines

Proper physical mounting and wiring practices ensure stable servo actuator performance and noise rejection:

• Rack Mounting and Chassis Grounding: Secure the 0.5 kg termination unit into its designated cabinet rack slot. Attach a grounding jumper from the board mounting frame to the main DCS cabinet earth grounding bar.
• Field Actuator Signal Wiring: Connect voltage and current servo drive lines using twisted-pair shielded cable. Route actuator control conductors in separate cable conduits isolated from high-voltage AC power lines.
• Cable Shielding: Terminate signal wire shields at the designated chassis grounding connection on the termination board to prevent electrical interference from corrupting sensitive servo positioning loops.