Purchase now: Allen Bradley 1746-OB16 DC Output Module
Purchase now: Atlantechdrives provides you the 1746-OB16, the industry-standard 16-channel digital DC output module for the Allen Bradley SLC 500 control system. This module is engineered to operate on 24V DC logic and utilizes a Sourcing configuration. As the workhorse of modern factory automation, the 1746-OB16 is relied upon to control a vast array of DC actuators, including pneumatic directional control valves, miniature DC motor relays, solid-state contactors, and control panel indicator lamps. By utilizing solid-state transistor outputs, this module provides exceptionally fast switching speeds and an effectively infinite mechanical lifespan compared to traditional relay modules, making it perfect for high-speed sorting, CNC machine interfacing, and continuous manufacturing operations.
Technical Specifications of the 1746-OB16
The 1746-OB16 features optically isolated circuitry to protect the PLC’s internal 5V processor from the harsh electrical realities of the factory floor. The «Sourcing» design means the module provides the positive voltage (+24V DC) out to the field device, which then completes the circuit by returning to the DC common (ground).
- Part Number: 1746-OB16
- Module Type: Digital DC Output Module
- Compatible System: SLC 500 (1746 Chassis)
- Number of Outputs: 16 Solid-State Transistor points
- Operating Voltage: 10…50V DC
- Wiring Logic: Sourcing (Provides V+ to load)
- Continuous Current per Point: 0.50 Amps at 30°C / 0.25 Amps at 60°C
- Signal Delay: On: 0.1 ms, Off: 1.0 ms (Extremely fast)
- Backplane Current Draw: 280 mA at 5V DC
Expert Installation Advice: Inductive Kickback Protection
The fastest way to destroy a solid-state DC module is by ignoring the physics of magnetic fields. Expert Tip: When the 1746-OB16 powers an inductive load (like a solenoid valve coil or a mechanical relay coil), a magnetic field is generated. When the PLC turns that output OFF, the magnetic field instantly collapses, generating a massive reverse-voltage spike (inductive kickback) that shoots back up the wire into the PLC. This spike can easily exceed 300 Volts and will instantly blow the internal output transistor on the OB16. You MUST install a flyback diode (such as a 1N4004) directly across the terminals of every inductive DC load you control. The diode will safely dissipate the reverse voltage spike, protecting the PLC module and ensuring decades of reliable operation.
Maintenance and Troubleshooting
The front panel of the 1746-OB16 features 16 individual red LEDs corresponding to the logic state of each output. During troubleshooting, if the PLC logic shows an output is active, but the LED on the module is off, check the module’s 5V backplane connection. If the LED is on, but the field device isn’t moving, the transistor might be blown, or the external 24V DC power supply feeding the VDC/COM terminals on the module’s wiring arm may have a blown fuse or tripped breaker.
Frequently Asked Questions (FAQs)
Q: What is the difference between the 1746-OB16 and the 1746-OV16?
A: The 1746-OB16 is a «Sourcing» module (it outputs positive voltage). The 1746-OV16 is a «Sinking» module (it provides the path to ground/negative). You must match the module type to the wiring logic standard of your machine panel.
Q: Can I wire two outputs in parallel to get 1.0 Amp of current?
A: Yes, Allen Bradley allows for parallel wiring of solid-state outputs on this module to drive slightly larger loads, provided the total module current does not exceed the 8.0 Amp maximum rating.
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This 24V DC output card provides reliable logic for field actuators when housed in a 1746-A4 chassis.
