Honeywell 621-9938RC Serial I/O Module, Dual-Port Redundant

Honeywell 621-9938RC Serial I/O Module

The Honeywell 621-9938RC Serial I/O Module is a redundant, dual-port communication interface designed for use within the Honeywell IPC 620/621 Programmable Controller System. It manages serial I/O card files and interfaces with the Honeywell 621-9939 Serial Link Module located in the processor card file.

Serial I/O Control and Redundancy

• Dual communication ports supporting redundant serial I/O channels
• Designed for continued operation in the event of a single-channel fault
• Controls remote serial I/O card files within IPC 620 system architecture

Configuration and System Behavior

The module is configured using four 8-position DIP switches and one 4-position DIP switch located on the circuit board. These switches define starting I/O addresses, rack output states during faults, operating mode selection, and the number of I/O points per slot.

Industrial Control Applications

• Redundant serial I/O communication in IPC 620/621 systems
• Processor-to-remote I/O rack interfacing
• Industrial control systems requiring hot-swappable I/O modules