746-ov8_a_8-channel_dc_output_module

Description

Technical Specifications

Main Features and Advantages

Sinking (NPN) output configuration for standard N.A. industrial practice: The Allen-Bradley 1746-OV8​ switches the low side of the load, which is the conventional sinking configuration in North American 24 V DC control systems. This allows direct interfacing with 24 V DC pilot devices already wired for sinking operation and pairs naturally with sourcing (PNP) input modules such as the 1746-IB8 or 1746-IB16 in the same chassis.Group-isolated commons for flexible wiring: The eight outputs of the Allen-Bradley 1746-OV8​ are divided into two electrically isolated groups of four (COM A and COM B). This permits the use of two separate 24 V DC field supplies—for example, one for critical outputs and one for non-critical—or allows one common to be used while the other is left unused. The isolation between groups also helps contain fault propagation should a common-side short occur.Electronic protection with auto-recovery: Each output channel on the Allen-Bradley 1746-OV8​ is protected against short circuits and excessive current draw. In the event of an overcurrent condition, the affected output is disabled and the module’s status LED may flash to indicate a fault; once the short is cleared, normal operation resumes automatically without the need to cycle power. Overtemperature protection guards the module if ambient conditions or sustained overload elevate internal junction temperature.High-speed solid-state switching: With typical on/off response times of 0.1 ms, the Allen-Bradley 1746-OV8​ is suitable for high-cycle-rate applications such as fast-acting reject gates, high-speed stacker actuators, or test fixtures where millisecond-level timing matters. Unlike relay outputs (e.g., 1746-OW8), the solid-state MOSFET design has no mechanical wear and offers essentially unlimited electrical life under rated load.Per-point LED diagnostics: Eight individual green LEDs on the faceplate of the Allen-Bradley 1746-OV8​ mirror the logical state of each output bit in the SLC 500 processor’s output file (e.g., O:3.0 through O:3.7). This provides immediate visual correlation between ladder logic output instructions and physical output activation, greatly accelerating commissioning and troubleshooting on the plant floor.Optical isolation from backplane: The field circuitry of the Allen-Bradley 1746-OV8​ is optically isolated from the 5 V DC SLC 500 backplane logic, protecting the processor and other modules from electrical noise or transient spikes coupled from the load side—a common concern when switching inductive DC loads such as solenoid coils.

Application Field

The Allen-Bradley 1746-OV8​ is the standard choice for general-purpose 24 V DC discrete output control within SLC 500-based automation systems across discrete manufacturing, packaging, material handling, water/wastewater, and food & beverage sectors. On bottling and canning lines, the Allen-Bradley 1746-OV8​ typically drives 24 V DC pneumatic solenoid valves that actuate filler heads, diverter gates, and case-erector clamps; each of the two commons may be wired to separate fused 24 V DC supplies to segregate critical timing valves from auxiliary indication loads.Conveyor systems and sortation lines use the Allen-Bradley 1746-OV8​ to energize 24 V DC stack lights, audible alarms, small DC interposing relays for motor starter coils, and photo-eye emitter enable signals. Because the module is sinking-type, it integrates cleanly with panel wiring practices that reference +24 V DC as the common switched leg and return load negatives through the PLC output—this is the predominant convention in North American machine control panels.In process batch skids and OEM-packaged equipment retaining SLC 500 hardware for long-term supportability, the Allen-Bradley 1746-OV8​ controls pump run permissives (via interposing relays), opens/closes valve indicators on local mimic panels, and triggers external counters or printers requiring a dry or low-voltage DC closure. Its solid-state reliability and immunity to contact pitting make it preferable to relay-output modules in applications involving frequent cycling (>10 ops/sec or continuous daily pulsing). For inductive DC loads, the inclusion of a flyback diode across the coil (externally) is recommended to suppress voltage spikes and prolong module life. When paired with a properly sized 1746-P2 or 1746-P4 power supply and a SLC 5/04 or 5/05 processor, the Allen-Bradley 1746-OV8​ forms a robust, easily maintained discrete output subsystem in both new-build and legacy-retrofit control panels.

Related Products

1746-OB8​ — 8-channel sourcing (PNP / high-side switch) 24 V DC output module; use instead of the 1746-OV8​ when the application requires sourcing-type outputs (switching +24 V DC to load positive).1746-OW8​ — 8-channel electromechanical relay (N.O.) output module; select when AC load switching or voltage-free dry contacts are needed, or when load polarity independence is required—at the cost of slower switching and finite contact life.1746-IB8 / 1746-IB16​ — 24 V DC sinking/sourcing digital input modules; typically installed alongside the 1746-OV8​ in the same SLC 500 chassis for complete local discrete I/O.1746-A7 / 1746-A10​ — 7-slot and 10-slot SLC 500 chassis into which the 1746-OV8​ is installed; the module occupies any I/O slot (not Slot 0 if occupied by processor).1747-L553 / 1747-L551​ — SLC 5/05 and SLC 5/03 processors that scan the 1746-OV8​ outputs as part of the local I/O image table; no special configuration beyond slot addressing is required.1746-P4​ — 1746-series 5 V / 24 V DC backplane power supply; must provide sufficient 5 V DC backplane current for the 1746-OV8​ (135 mA) plus all other modules in the chassis.