When Eight Outputs Must Stay Independent
A system integrator running a ControlLogix line faced a familiar problem: a single fault on one output channel was dragging down neighboring field devices. The fix was channel-to-channel isolation, and the 1756-OH8I delivers exactly that. This Allen-Bradley module provides eight individually isolated 120V DC outputs, so one compromised point cannot take the rest of the rack offline.
What the 1756-OH8I Brings to the Chassis
The 1756-OH8I is an isolated output module in the ControlLogix series, built for DC digital output duty. Each of its eight points sinks or sources 120V DC independently. The operating voltage range spans 90-146V DC, giving practical headroom for real-world supply variation.
Current handling is generous for a module this size. Each point carries up to 2A at 60°C, while the module total reaches 8A at the same temperature. Minimum load per point is 2mA, and each point tolerates a 4A surge. In the ON state, drop voltage is 2V DC at 2A; OFF-state leakage stays at 1mA per point.
Isolation is the headline feature. Output-to-backplane and output-to-output isolation is rated 250V, with basic insulation tested at 1350V AC for 2 seconds. The module draws 210mA at 5V from the backplane and dissipates 3.3W at 60°C. Output signal delay is 2ms for both ON-to-OFF and OFF-to-ON transitions.
Where This Module Earns Its Place
Oil and gas facilities often run valve banks, motor starters, and indicator circuits from one chassis. Because the 1756-OH8I isolates every point, a shorted field device on one channel will not disturb the others. That matters during upset conditions when operators need every remaining output to keep functioning.
Water treatment and pipeline stations use the same logic. Mixed-voltage field wiring stays separated, and maintenance crews can troubleshoot one point without pulling the whole module. For plants upgrading older output cards, the 1756-OH8I is a practical replacement path within the ControlLogix platform.
Installation and Environmental Notes
The module mounts in a ControlLogix chassis and uses removable terminal blocks, part numbers 1756-TBCH and 1756-TBS6H. The enclosure is open-style, so it relies on the host panel for protection. Operating temperature range is 0-60°C at 5-95% relative humidity. The module withstands 2G vibration at 10-500Hz and shock up to 20G. It carries a T4A North America temperature code.
Before You Order
Confirm your chassis slot, terminal block type, and field voltage against your application. If you need selection help, Oil AutoTech offers hands-on technical support. Spares when you need them — fast dispatch, worldwide. Please verify current lifecycle status and availability with Oil AutoTech before ordering.
Contact Oil AutoTech today for pricing and availability.
