The Allen‑Bradley 1746‑OA8, also cataloged as the 1746‑OA8 output module, serves as the primary AC output card used to execute discrete actuation across SLC 500 backplane platforms. It provides eight output points with fixed AC‑rated switching behavior and defined leakage characteristics.
Hardware Specifications
Parameter
Specification
Model
1746‑OA8
Brand
Allen‑Bradley
Origin
Not specified
Weight
Not specified
Dimensions
Not specified
Operating Temp
Not specified
Power Consumption
0.185 A @ 5 VDC (backplane)
Product Type
AC Output Modules
Series
SLC 500 (1746)
Voltage Category
120/240 VAC
Number of Outputs
8
Points per Common
4
Operating Voltage
85–265 VAC @ 47–63 Hz
Signal Delay
1 ms ON, 11 ms OFF (resistive load)
Off‑State Leakage
2 mA max
Backplane Bus Communication Velocity Licenses
The 1746‑OA8 participates in deterministic backplane timing used across SLC 500 architectures. Output transitions follow fixed AC‑cycle‑dependent propagation intervals, ensuring predictable actuation during processor scan execution. I/O density scaling allows multiple AC output modules to coexist without altering backplane propagation delay. Firmware flash compatibility resides entirely within the SLC processor; the OA8 contains no programmable logic and maintains stable electrical behavior across controller revisions.
Frequently Asked Questions
Q: Can the 1746‑OA8 be hot‑swapped? A: No. AC output modules must be inserted or removed only when the chassis is de‑energized to avoid undefined output states.
Q: Does the module support DC loads? A: No. The 1746‑OA8 is designed exclusively for AC output operation.
Q: How does off‑state leakage affect connected loads? A: High‑impedance loads may detect small leakage currents; resistive or properly rated loads eliminate false activation.
Field Installation Guidelines
Route AC wiring separately from low‑level analog or digital circuits to reduce noise coupling.
Ensure proper conductor torque at terminal blocks to prevent thermal loosening.
Maintain correct load ratings to avoid exceeding per‑point current limits.
Verify backplane power capacity when installing multiple high‑current modules.
Label field wiring to support maintenance and fault tracing.
Maintain non‑condensing humidity conditions to prevent terminal oxidation.
