Product Overview
When precise, time-synchronized output control is critical in motion and positioning applications, the Allen-Bradley 1756-OB16IEFS delivers. This ControlLogix fast digital output module provides 16 scheduled, high-speed, individually isolated, and electronically fused outputs. It is the only module that can operate in a remote chassis with the Motion Axis Output Cam (MAOC) instruction and receive output data while doing so.
Part of the ControlLogix series, the 1756-OB16IEFS is designed for position-based output control. It supports CIP Sync as a slave-only device, enabling accurate scheduling and timestamping. With an operating voltage range of 10 to 30 V DC, it is suitable for a wide variety of DC loads.
Technical Specifications
The table below lists the key technical parameters for the Allen-Bradley 1756-OB16IEFS. All values are taken directly from the manufacturer's data.
| Specification |
Value |
| Part Number |
1756-OB16IEFS |
| Brand |
Allen-Bradley |
| Series |
ControlLogix |
| Module Type |
DC Output Module |
| Circuit Type |
DC |
| Input Voltage |
10-30 Volts |
| Operating Voltage Range |
10-30 Volts DC |
| Maximum Output Current Rating - Point |
2 Amps at 30 °C, 1 Amp at 60 °C |
| Maximum Output Current Rating - Module |
8 Amps at 30 °C, 4 Amps at 60 °C |
| Power Dissipation (Max) |
3.6 Watts at 60 °C |
| Backplane Current at 5 Volts |
350 milliamps |
| Backplane Current at 24 Volts |
3 milliamps |
| Removable Terminal Blocks |
1756-TBCH, 1756-TBS6H |
| Isolation Voltage |
50 Volts Continuous |
| Enclosure |
None |
Key Performance Characteristics
The 1756-OB16IEFS offers an inrush pilot duty of 4 A. Its voltage category is 12/24 V DC sink/source. The module draws 320 mA at 5.1 V and 3 mA at 24 V, with a total backplane power of 1.7 W. Maximum off-state leakage current is less than 0.1 mA per point. Surge current is 4 A for 10 ms per point, repeatable every 2 seconds.
Maximum on-state voltage drop is 0.4 V DC at 2 A and 0.2 V DC at 1 A. Maximum current per point is 2 A at 45 °C (4 channels max) and 1 A at 60 °C. Maximum current per module is 16 A at 60 °C (max 1 A per channel) and 8 A at 45 °C (max 2 A per channel). Minimum load current is 1 mA per point. Continuous isolation voltage is 250 V.
Unscheduled output delay time is nominal 14 µs, maximum 23 µs, from off to on and vice versa. The module supports Pulse Width Modulation (PWM) with a cycle time of 1 ms min to 1 hour max, PWM on time of 200 µs min to 1 hour max, and PWM on-time accuracy of ±20 µs.
Industry Applications
Because of its high-speed, scheduled output capabilities, the 1756-OB16IEFS is ideal for applications that require precise timing. Common uses include:
- Packaging machinery requiring cam-based output synchronization.
- Motion control systems using MAOC instructions for position-based triggering.
- High-speed sorting and inspection systems where output timing accuracy is critical.
In each scenario, the module's isolated outputs and electronic fusing protect both the module and the connected devices from overcurrent conditions.
Installation & Setup Guidance
Install the 1756-OB16IEFS in any ControlLogix chassis. The module requires a removable terminal block (RTB) for wiring, specifically the 1756-TBCH or 1756-TBS6H. Ensure the RTB is properly seated before powering the system.
When configuring the module in your control software, set the fault mode states (Hold Last State, On, or Off), fault mode duration (1, 2, 5, 10 seconds, or Forever), final state after fault mode, and program mode states. All default to Off except fault mode duration, which defaults to Forever.
Verify that the load voltage is within the 10-30 V DC range and that the total current per point and per module does not exceed the rated values. Use appropriate wiring practices to minimize noise and ensure reliable operation.
Maintenance & Reliability
Routine maintenance is minimal for the 1756-OB16IEFS. Periodically inspect the terminal blocks for tightness and check for any signs of overheating or discoloration. Ensure the chassis ventilation is unobstructed to maintain ambient temperature within specified limits.
Because the module uses electronic fusing, there are no replaceable fuses. If a channel faults, the module will indicate the condition, allowing quick diagnosis and replacement of the load rather than the module.
Compatibility & Integration
The 1756-OB16IEFS is designed for the ControlLogix platform and communicates over the backplane. It supports CIP Sync for time synchronization, making it compatible with other CIP Sync-enabled devices. For remote chassis operation, it works with the MAOC instruction, a unique capability.
When integrating, ensure your controller firmware supports the module's features. The module is a slave-only device for CIP Sync, so it receives timing from a master.
Selection Guide & Purchasing Advice
Before purchasing the 1756-OB16IEFS, verify that your system uses ControlLogix and that you have a compatible RTB (1756-TBCH or 1756-TBS6H). Confirm your load requirements—voltage range 10-30 V DC, current per point up to 2 A at 30 °C, and per module up to 8 A at 30 °C.
For reliable sourcing, PLC Source PRO offers genuine Allen-Bradley modules with fast shipping. Ensure you order the correct part number to match your application needs.