Honeywell 621-9950 Discrete I/O Termination Module

Overview

The Honeywell 621‑9950 is a high-reliability discrete I/O termination module designed for Honeywell 620/621 Distributed Control Systems (DCS). It provides the physical interface between the controller and field digital devices, ensuring clean signal routing, stable voltage handling, and protection against electrical surges. The module supports 16 individual channels, handles 11–28 VDC digital signals, and offers up to 2 A of drive capability per channel.

This module is widely used in industrial environments for applications such as pumps, relays, motors, valves, and solenoids, ensuring stable system operation, electrical isolation, and high noise immunity.

Technical Specifications

Electrical Specifications

• Channels: 16 discrete I/O termination points

• Voltage Range: 11–28 VDC

• Output Current: 2 A per channel

• Surge Current: 5 A for 10 ms (non-repetitive)

• Off-State Leakage: ~5 mA (typical)

• On-State Voltage Drop: ~2 VDC at 2 A

• Required Terminal Block: Honeywell 621‑9949

Mechanical Specifications

• Dimensions (Packaged): 28.5″ × 25.5″ × 22.5″

• Weight: 1 lbs

• Mounting: Fits Honeywell 620/621 DCS racks

Key Features

• 16-channel discrete I/O interface, supports stable digital signal transmission

• Compatible with 11–28 VDC signals

• Provides 2 A per channel for driving high-power loads

• Surge-tolerant design ensures industrial-grade reliability

• Compatible with Honeywell 620/621 DCS systems

Applications

Ideal for use in industrial automation systems such as:

• Pump station control and monitoring

• Relay and solenoid valve driving

• Motor and mechanical device digital signal collection

• Field interface termination for process control systems

FAQ

Q1: Does this module support repetitive surges?
A1: The module is designed to handle a non-repetitive surge of 5 A / 10 ms. Continuous surge usage should be within design specifications.

Q2: Can it operate below 10 VDC?
A2: It is recommended to keep the voltage within the 11–28 VDC range for optimal performance.

Q3: Is this module compatible with controllers other than Honeywell 620/621 series?
A3: The module is specifically designed for the Honeywell 620/621 DCS systems and has not been verified for third-party controller compatibility.