OVERVIEW

Official designation: Allen-Bradley 1775-RM (PLC-3, Peripheral Interface Adapter Module)

Role/Application: The 1775-RM adapter facilitates remote communication between RS-232-C compatible devices and the PLC-3 Peripheral Communication Module (1775-GA) over twin-axial cable up to 10,000 feet.

KEY SPECS SUMMARY

Power: 5 Volts DC, 1.5 Amps (backplane)

Interfaces / Ports: Twinaxial cable connector, two RS-232-C channels

Indicators: MOD FLT, REM ACT, CH0 ACT, CH1 ACT LEDs

Operating Temp: 0 to 60 degrees C

Platform / Compatibility: PLC-3 system, 1771 I/O chassis slot

Limit: Maximum cable length 10,000 feet

Lifecycle: Discontinued/Obsolete

FREQUENTLY ASKED QUESTIONS

Technical Specifications:

Q: What is the maximum communication data rate and corresponding maximum cable length supported by the 1775-RM module?

A: The module supports 115.2 kbaud up to 5,000 feet or 57.6 kbaud up to 10,000 feet.

Wiring & Installation:

Q: How is the 1775-RM physically installed, and what is its power source within the PLC-3 system?

A: It is installed into a single slot of any 1771 I/O chassis and receives its power via the chassis backplane.

Troubleshooting & Compatibility:

Q: What do the four LED indicators on the 1775-RM module signify during system operation?

A: MOD FLT indicates a module fault, while REM ACT, CH0 ACT, and CH1 ACT show active communication status.

Replacement & Upgrades:

Q: What is the manufacturer's long-term recommended migration path for the obsolete PLC-3 system using the 1775-RM adapter?

A: The recommended migration path for the legacy PLC-3 platform is conversion to the modern ControlLogix automation platform.