Allen-Bradley 1769-OB32 Compact I/O 32-Point 24V DC Source Output Module

Thirty-two solid-state outputs in a compact module

The Allen-Bradley 1769-OB32 is a 32-point 24V DC source output module for the 1769 Compact I/O system. Its transistor outputs, arranged in two groups of 16, switch relay coils, indicator lamps, small solenoids and interface relays where the load returns to the DC common.

It complements the 32-point 1769-IQ32 input module. Because the outputs are solid state they have no contact wear and switch quickly, but they are limited in current; check the derating below before connecting solenoids or lamps with high inrush.

Technical specifications

Derating and switching limits

The sheet publishes current limits that fall with temperature: 1.0 A per point and 8.0 A per module at 30 °C, but only 0.5 A per point and 4.0 A per module at 60 °C. A surge of 2.0 A for 10 ms is permitted every 2 seconds. The output drop is 1.0V DC maximum at 1 A and the off-state leakage is 1.0 mA at 26.4V DC.

Where leakage can hold a sensitive load on, the sheet suggests a 5.6 kΩ, 0.5 W loading resistor in parallel with the load for 24V DC operation. For inductive loads it recommends a 1N4004 diode wired in reverse across the load. Delay is 0.1 ms to turn on and 1.0 ms to turn off.

Bank placement and wiring

The module draws 300 mA at 5.1V DC and dissipates up to 4.5 W. Its power-supply distance rating is 6 modules, shorter than the input modules because of the higher current draw, so count positions from the supply when planning the bank. It is 1.5 slots wide, weighs 450 g and mounts on a DIN rail or panel.

The field terminal is an 18-pin block with 22 to 14 AWG solid or 22 to 16 AWG stranded 90 °C copper. Isolation from output point to bus is verified at 1200V AC for 1 s with a 75V DC working voltage. The related terminated type, the 1769-OB32T, is a separate catalog number.

Documents and quotation

The Compact I/O technical data 1769-TD006 holds the OB32 table and derating curves. For a quotation send the 1769-OB32 reference, series, quantity, the controller or adapter and the load list. Related products appear in PLC & I/O Cards and 1769-OB16 output module.

How the 1769-OB32 Works

A sourcing output connects the load to the positive side of the DC supply. When the controller sets an output bit, the transistor for that point turns on and current flows from the +VDC terminal of the group, through the output, through the load and back to DC COM. The 1769-OB32 has two groups of 16 points, each with its own +VDC and DC COM terminals, so the two halves of the module can be fed from separate 24V DC circuits if the panel design calls for it.

Because the switch is a transistor rather than a relay contact, there is no mechanical wear and switching is fast, which suits frequently cycled loads such as indicator lamps, interface relays and small valves. The trade-off is a small on-state voltage drop and a small off-state leakage current, which is why the technical data recommends a loading resistor for very low-current loads and a suppression diode across inductive loads.

1769-OB32 Selection & Ordering Guide

• Point count: choose the 1769-OB32 when you need many sourcing outputs in little rail space; the 16-point 1769-OB16 is the smaller alternative.
• Load current: add up the simultaneous load current of each group and check it against the temperature derating in the specification table. Loads with high inrush, such as large solenoids or incandescent lamps, may be better switched through interface relays.
• Coated or terminated versions: the 1769-OB32K is conformal coated; the 1769-OB32T is a separate catalog number and should not be assumed to be interchangeable.
• Bank position: with a power supply distance rating of 6 modules, plan the slot so that the module is no more than six positions from the 1769 power supply.
• Platform: the module is used in 1769 Compact I/O banks with a CompactLogix controller, as MicroLogix 1500 expansion I/O, or with a 1769 communication adapter, as listed in the Compact I/O specifications.

When you request a quote, include the series letter from the module label and the spare terminal block if required. Our team can help confirm the correct ordering code.

Installation & Maintenance

Remove power before installing or removing the module or its terminal block. Connect the +VDC and DC COM of each group as shown in the wiring diagram, protect each supply circuit with a suitably rated fuse or breaker, and fit a reverse diode across DC solenoid coils and relay coils. Keep output wiring separated from low-level analog cables.

During maintenance check that the yellow output status indicators follow the program, measure the supply voltage at the group terminals under load, and look for heat discoloration on terminals. If an output appears stuck on with a light load, the off-state leakage may be the cause; a loading resistor across the load usually resolves it.

Typical Applications in Oman & the GCC

• Pump and valve control panels in water distribution and wastewater treatment.
• Pilot lamps, horns and interface relays on oil and gas utility skids.
• Conveyor, palletising and packaging lines with many small 24V DC actuators.
• HVAC and district cooling plants: damper actuators, alarm beacons and relay outputs to motor starters.

Panels in hot plant rooms should be cooled or ventilated, because the per-point and per-module current ratings of the 1769-OB32 fall as ambient temperature rises.

Why Source the 1769-OB32 from Seven Star LLC

Seven Star LLC supplies Allen-Bradley Compact I/O modules, including the 1769-OB32, across Oman and the GCC. Request a quote with the catalog number, series and quantity, and our team can help confirm the correct ordering code, terminal block and companion modules.