Allen Bradley 1769-OB16 16-Point Sourcing Output Module
The Allen Bradley 1769-OB16 is a digital DC output module belonging to the Compact I/O family (1769 series). It provides 16 sourcing (PNP) outputs with an operating voltage range of 20.4–26.4 VDC (nominal 24 VDC). This module is designed for use with CompactLogix, MicroLogix 1500, and other 1769-based control systems. Each output is independently isolated from the logic side and offers short-circuit protection, diagnostic feedback, and high current density in a compact footprint.
Output Specifications
Each of the 16 channels is a source type output: when energized, the output terminal supplies +24 VDC to the load. The maximum continuous current per point is 0.5 A (500 mA), and the maximum total current per module is 4 A (when all points are active simultaneously). The off-state leakage current is less than 1 mA, ensuring reliable operation with high-impedance loads such as solid-state relays. On-state voltage drop is typically 0.3 V at rated current, minimizing power dissipation.
Protection and Diagnostics
Each output channel includes electronic short-circuit protection (current limiting at approximately 1.1 A) and thermal shutdown with automatic reset. An open-load detection feature reports a fault when the connected load resistance exceeds 25 kOhm. The module provides per-point status LEDs (green) that illuminate when the output is actively sourcing. A global module fault LED (red) indicates over-temperature, overcurrent, or communication loss. Fault conditions can be read via the backplane as a status word, allowing the PLC to trigger alarms or shutdowns.
Power and Electrical Isolation
The 1769-OB16 requires an external 24 VDC supply connected to terminals VDC and COM on the module’s removable terminal block. The supply voltage range is 20.4–26.4 VDC, including +20% ripple. The module draws a maximum of 150 mA from the 5 V backplane supply plus the load current from the field side. Isolation between field side and logic bus is 2500 VAC RMS for 1 second. There is no isolation between individual output channels; they share a common supply return (COM terminal).
Response Times and Filtering
Output turn-on delay from CPU scan to terminal is typically 0.1 ms (maximum 0.5 ms). Turn-off delay is similarly 0.1 ms. The module includes a configurable output filter (0, 1, or 5 ms) selectable via the controller’s I/O configuration, which can suppress transient noise from inductive loads. For applications requiring faster switching, the filter can be disabled (0 ms). The maximum switching frequency is 500 Hz at resistive load; for inductive loads, the frequency should be reduced to allow demagnetization through the internal flyback diode (included in the module).
Compatibility and System Integration
The 1769-OB16 is compatible with all CompactLogix 5370, 5380, and 5480 controllers, as well as MicroLogix 1500 LRP series. It can be placed in any slot of a 1769 bus, up to a maximum of 8 modules per controller (depending on power budget). The module supports both local (rack) and remote (EtherNet/IP or ControlNet via 1769-AENTR) configurations. RSLogix 5000 or Studio 5000 Logix Designer automatically recognizes the module and provides a built-in data structure for output control and diagnostics. Configuration via the controller’s I/O tree is required only for filter settings; otherwise the module is ready to use with default parameters.
Environmental and Mechanical Data
Operating temperature: 0 to 60°C (32 to 140°F)
Storage temperature: -40 to 85°C (-40 to 185°F)
Relative humidity: 5% to 95% non-condensing
Vibration: 5 g @ 10–500 Hz (IEC 60068-2-6)
Shock: 30 g (IEC 60068-2-27)
Dimensions (W x H x D): 35 mm x 118 mm x 87 mm (1.38 in x 4.65 in x 3.43 in)
Weight: 130 g (4.6 oz)
The housing is rated IP20 (finger-safe) and uses an open-style terminal block requiring no special tools. The removable terminal block (1769-RTBN18) accepts 0.25–1.5 mm² wire (22–16 AWG).
Typical Applications
Common uses include driving solenoid valves, indicator lamps, relay coils, contactors, and small motors (with external contactors). In packaging machines, the module controls pick-and-place actuators. In conveyor systems, it drives zone diverters. Its sourcing configuration is standard for many European and Asian industrial controls, making it a direct replacement for 1756-OB16 in smaller chassis. The high density (16 points in a single-wide slot) saves panel space.
Installation and Wiring Guidelines
Mount the module on a 35 mm DIN rail or screw to a panel using mounting tabs. The bus connector (included) establishes communication between adjacent modules. Ensure the external 24 VDC supply is shared with the load circuit; the COM terminal must be connected to the negative side of the power supply. For inductive loads, external flyback diodes are not required because the module includes internal suppression (zener diode + MOV) clamping to 50 V. However, if switching large relays (>50 mA), external diodes may reduce internal heating.
Troubleshooting and Maintenance
The most frequent issues are blown external fuses (not included) or shorted wiring. The module’s short-circuit protection will limit current and report a fault via the status word but does not physically disconnect the channel; the channel will attempt to operate again when the short is removed. To reset a thermal shutdown, cycle power or wait for the module to cool. No routine maintenance is required except periodic tightening of terminal screws. Firmware updates are not applicable as the module has no user-programmable firmware.
Ordering and Standards Compliance
Catalog number: 1769-OB16. The module is UL 508 listed, CE marked, and certified for cUL, ATEX Zone 2, and IECEx. RoHS compliant. For replacement parts, the terminal block is 1769-RTBN18. Documentation: Allen Bradley publication 1769-IN015 (installation instructions) and 1769-UM001 (user manual). The module carries a 2-year warranty from Rockwell Automation.
