Overview
The Allen-Bradley 1771-OW is an electromechanical relay contact output module from the 1771 series, engineered for PLC-5 control systems. This module provides eight independently isolated output channels organized in four groups of two, with selectable normally open (N.O.) or normally closed (N.C.) relay configurations. Each output is internally isolated from the module logic circuitry, ensuring clean switching and reliability in industrial control applications.
Key Features
- Eight (8) relay output channels grouped in four (4) pairs with individual common returns
- Selectable normally open (N.O.) or normally closed (N.C.) contact configuration per channel, with N.O. as factory default
- Operates at 24–138VAC RMS and 24–125VDC output voltages
- Maximum continuous output current of 1.0 Ampere per channel
- Fast relay response: 5 ms operate/release time, 1 ms bounce time, 10 Hz switching frequency
- Internal electrical isolation between module logic and output circuitry
- Compatible with 1771 I/O chassis (1771-A1B through A4B and later models)
Technical Specifications
- Output Channels: 8 (4 groups of 2)
- Output Voltage Range: 24–138VAC RMS, 24–125VDC
- Maximum Output Current: 1.0 Ampere per channel (continuous)
- Relay Type: Electromechanical contacts
- Operating/Release Time: 5 ms
- Contact Bounce Time: 1 ms
- Switching Frequency: 10 Hz maximum
- Contact Configuration: Selectable N.O./N.C. (default N.O.)
- Field Wiring Connector: 1717-WD Field Wiring Arm
- Mounting: 1771 I/O Chassis (half-slot or full-slot addressing)
- Module Isolation: Channel-isolated contact type
Typical Applications
- Legacy PLC-5 system expansions and replacements
- Machinery control with low-power relay outputs
- Process automation requiring selectable normally open/closed logic
- Industrial equipment retrofitting where contact output is required
- Control circuits with resistive loads and standard AC/DC loads
Compatibility & Replacements
The Allen-Bradley 1771-OW is part of the 1771 discrete I/O module family and is compatible with all 1771-series I/O chassis. If you require additional output channels, consider the 1771-OW16 (16-channel version). The module requires the 1717-WD field wiring arm for installation. Note that this module uses electromechanical relays; for environments with noxious contaminants, dry-reed alternatives (1771-OYL, 1771-OZL) or mercury-wetted relays (1771-OX) may be preferred. No surge-limiting circuitry is included internally; external RC network filters are recommended for inductive loads.
