Honeywell 621-2150 Digital Output Module

The Honeywell 621-2150 is a 16-point digital AC output module designed for PLC and industrial control applications. It provides independent AC output channels with zero-crossing switching technology, allowing controlled switching of AC loads while reducing electrical noise and stress on connected devices. The module combines optical isolation, fused output protection, and high-current output capability for field device control.

Output Architecture

The module provides 16 independent digital output channels for controlling AC-powered field devices. Each output uses zero-crossing switching, which turns the output on near the AC waveform's zero-voltage point. This reduces switching transients and minimizes electrical interference compared with random turn-on switching methods.

The outputs are intended for AC load control applications operating within the specified voltage range and frequency limits.

Electrical Characteristics

The module is designed for a nominal operating voltage of 115 VAC at 50/60 Hz and supports an operating voltage range of 90 VAC to 140 VAC.

Each output point can switch up to 2.0 A, while the total module current must not exceed 12.0 A. For applications involving inductive or high-inrush loads, the module accommodates surge currents up to 15.0 A for a maximum of two AC cycles.

Protection and Isolation

Each output circuit is protected by an individual 3 A slow-blow fuse. This approach helps isolate field-side faults to a single output channel and simplifies maintenance when troubleshooting wiring or load issues.

Optical isolation separates the backplane logic circuitry from field AC circuits. The module provides a typical isolation voltage rating of 1500 V between the control electronics and high-voltage field wiring.

System Integration

The 621-2150 draws approximately 529 mA from the PLC backplane 5 VDC supply. Proper backplane power budgeting should be verified when multiple high-density I/O modules are installed in the same system.

For field termination, the module is designed to be used with the Honeywell 621-9950 terminal block.

Environmental Specifications

The module is specified for operation from 0 deg C to +50 deg C and within a non-condensing humidity range of 5% to 95% RH. These ratings should be considered when installing the module in enclosed control panels or equipment rooms.

Technical Specifications

Application Notes

Because the module uses zero-crossing switching, it is particularly suited for AC loads such as pilot devices, relays, contactors, solenoids, and indicator circuits where controlled AC switching is desirable. The switching method may not be appropriate for applications requiring precise phase-angle control or very fast switching independent of the AC waveform.

Frequently Asked Questions

Q: How many output channels does the 621-2150 provide?
A: The module provides 16 independent AC output channels, each capable of controlling separate field loads within the specified current limits.

Q: What is the maximum load current available on each output?
A: Each output point is rated for up to 2.0 A. The combined current of all active outputs must not exceed 12.0 A for the entire module.

Q: Does the module include protection for individual output circuits?
A: Yes. Each output channel is protected by its own 3 A slow-blow fuse, helping to limit the impact of field wiring faults to a single circuit.

Q: What terminal block is required for field wiring?
A: The module is designed for use with the Honeywell 621-9950 terminal block.