The Allen-Bradley 1771-WS, also cataloged as the 1771WS Weigh Scale Module, operates as a dedicated hardware component for single-vessel strain gauge signal acquisition and millivolt conversion within PLC-5 1771 I/O rack architectures.

Revision Index & Hardware Variants

• Primary Catalog Number: 1771-WS
• Alternate Spare Identifier: 1771WS
• Hardware Revision Code: 1771-WS/B
• Architecture Line: PLC-5 1771 System

Electrical & Environmental Attributes

Deterministic Signal Processing & Backplane Bus Integration

The 1771-WS converts 0 to 30 mV load cell bridge signals into digitized weight data, updating the 1771 backplane logic table via block transfer commands. Maintaining high backplane bus communication velocity allows rapid weight data throughput across multi-slot chassis setups while ensuring firmware flash compatibility across legacy and upgraded PLC-5 processors.

Supply Package Scope

• 1 x 1771-WS Single Vessel Weigh Scale Module
• 1 x Technical Installation Datasheet Sheet

Field Wiring Protocols & Mounting Rules

• Backplane Isolation: Turn off main chassis backplane power prior to inserting or removing the 1771-WS card.
• Signal Shielding: Use shielded twisted-pair cabling for 0 to 30 mV load cell wiring, running cables in isolated conduits to suppress EMI.
• Grounding Compliance: Earth the cable shields at the enclosure single-point ground bar to maintain signal resolution.

Frequently Asked Questions

• Q: What load cell input range is supported by the 1771-WS module?

  The module converts full-scale analog millivolt input signals ranging from 0 to 30 mV directly from strain gauge bridges.

• Q: What is the backplane current draw on the 5 VDC bus line?

  The unit draws a nominal 1.5 A from the 1771 backplane 5 VDC supply rail during continuous operation.

• Q: How many vessel channels can one 1771-WS card monitor?

  The 1771-WS is structured to interface with a single vessel weighing system across its 1 signal channel.

• Q: Can the 1771-WS module be seated while the chassis power is active?

  No, power to the 1771 chassis must be disconnected prior to seating or removing the module to prevent electrical damage.

• Q: What does the spare designation 1771-WS/B signify?

  The code 1771-WS/B indicates the Series B hardware revision update for the baseline 1771-WS weigh scale module.

• Q: How does the weight data transfer from the module to the PLC-5 processor?

  Data transfers across the 1771 backplane bus using standard block transfer read and block transfer write instruction routines.

• Q: What is the estimated shipping weight and physical size of the unit?

  The module weighs 0.74 kg with package shipping dimensions measuring approximately 3.0 x 15.2 x 25.8 cm.

• Q: What ambient temperature envelope is required for enclosure installation?

  The module operates reliably within a standard operating ambient enclosure temperature range of 0 to 60 deg C.