Allen-Bradley 1756-OX8I Eight-Point Isolated Relay Output Module
A ControlLogix relay output module with individually isolated changeover contacts for documented AC and DC field circuits.
Overview
Allen-Bradley 1756-OX8I is an eight-channel ControlLogix digital relay output module. Each channel presents normally open and normally closed contacts, allowing a documented load circuit to use the required contact state.
Rockwell Automation rates the module for 5–125 V DC or 10–240 V AC service and specifies continuous isolation between outputs. The outputs are not internally protected against short circuit, so field protection must be handled by the approved circuit design.
The module is an active Series A product. Its relay behavior, contact loading, configured program and fault states, terminal block and external fusing should be reviewed together before replacement.
Specifications
Features
Changeover contact access
Both normally open and normally closed paths are available for each of the eight isolated channels.
Mixed field-voltage capability
Documented AC and DC ranges support diverse relay loads while electrical separation is maintained between points.
Per-point state control
Program and fault behavior can be set to hold last state, turn on or turn off, with off as the default.
Serviceable relay design
The product is listed as repairable or replaceable, but rated-load switching frequency and contact-life limits still govern use.
Applications
Isolated field switching
Operating separate AC or DC load circuits that cannot share a common return.
Changeover signaling
Providing complementary N.O. and N.C. contact states to an approved external circuit.
Legacy relay-output conversion
Using documented 1492 conversion hardware where Rockwell publishes a compatible migration path.
Lifecycle
Document
Record 1756-OX8I, series, firmware, terminal block, every load voltage and the selected N.O. or N.C. path.
Protect
Confirm branch protection, suppression, conductor rating and lockout boundaries because the outputs are not short-circuit protected.
Test
Prove each contact under controlled conditions, checking state logic, field voltage, load response and final interlock behavior.
About IndustryParts
https://www.industryparts.com/Documented handling for 1756-OX8I
IndustryParts keeps the exact model, requested quantity, installed-system evidence and delivery record together so the proposed supply can be checked against the real application before dispatch.
FAQ
What field-load information should accompany a 1756-OX8I request?
Provide voltage type and level, steady and inrush current, contact state, switching frequency, suppression method and the 36-pin terminal-block identity.
Can 1756-OX8I be treated as a safety output module?
No. Rockwell Automation does not identify this module as suitable for safety functions; any safety duty requires an approved safety architecture.
Why does external protection matter for 1756-OX8I?
The manufacturer states that the relay outputs do not include short-circuit protection and recommends a fused interface module to help protect them.
Which configured states should be reviewed before exchanging 1756-OX8I?
Capture the per-point program-mode and fault-mode selections, including any hold-last-state or energized-state requirement.
How should 1756-OX8I relay health be accepted after service?
Operate each affected point at its real field voltage, confirm N.O. and N.C. behavior, check load response and retain results for the associated permissive or interlock.
