Overview
The Allen-Bradley 1756-OB16I is a 16-point discrete output module designed for the ControlLogix family of programmable logic controllers. Each output point is individually isolated, allowing independent 12/24 VDC voltage sources to be wired to each channel. This isolation architecture provides superior flexibility compared to non-isolated alternatives while maintaining robust industrial performance standards.
Key Features
- 16 individually isolated output points – each channel supports independent voltage sourcing
- Sink and source configuration – operates in both sinking and sourcing modes within the same module
- Fast response time – 1 ms maximum OFF-to-ON, 2 ms maximum ON-to-OFF output delay
- High isolation voltage – 250 V continuous output-to-backplane isolation, 125 V output-to-output isolation
- Integrated diagnostics – enhanced failure detection and onboard data alarming for set events
- Removable terminal blocks – 1756-TBCH and 1756-TBS6H (36-pin) for flexible wiring
Technical Specifications
This module operates at 10–30 VDC with rated output current of 2 A per point at 30 °C (derated to 1 A at 60 °C). Maximum module current is 8 A at 30 °C or 4 A at 60 °C. Minimum load requirement is 1 mA per point; maximum off-state leakage is 0.5 mA per point. Power dissipation reaches 3.6 W at 60 °C. The backplane draws 350 mA at 5.1 VDC and 2.5 mA at 24 VDC. Output delay time is 1 ms maximum (OFF to ON) and 2 ms maximum (ON to OFF). Standard certifications include UL, CE, CSA, CCC, RCM, ATEX, and marine classification.
Typical Applications
- Manufacturing equipment control – conveyor systems, press controls, sorting machines
- Machine tool automation – spindle control, hydraulic valve actuation
- Process equipment – heater/cooler switching, solenoid valve sequencing
- Environmental monitoring systems – discrete alarm outputs, status indication
- Multi-voltage control networks – independently sourced 12 VDC and 24 VDC loads on a single module
Compatibility & Replacements
The 1756-OB16I mounts directly to any 1756 CompactLogix or ControlLogix chassis (local or remote) via standard backplane connection. It is part of the discrete I/O product line and is controlled via EDS files (Electronic Data Sheets) available from Rockwell Automation. The module is compatible with Studio 5000 Logix Designer and all ControlLogix programming software. For applications requiring 32 output points without individual isolation, the 1756-OB32 offers an alternative; however, the 1756-OB16I’s isolation advantages make it the standard choice for multi-voltage or high-noise environments. Terminal block replacements (1756-TBCH, 1756-TBS6H) are field-serviceable.
