Purchase now: Allen-Bradley 1756-OB16IS ControlLogix Safety Isolated Output Module
Atlantechdrives provides you the 1756-OB16IS, a specialized 16-point sourcing DC output module designed for applications requiring high-integrity safety control and individual point isolation. Belonging to the GuardLogix and ControlLogix families, this module is a critical component for achieving functional safety in complex industrial environments where independent circuit protection and zero ground loops are mandatory.
- Outputs: 16 Points (Individually Isolated)
- Voltage Range: 10-31.2V DC
- Safety Rating: Capable of SIL3/PLe (when used with GuardLogix)
- Current Rating: 0.5A per point @ 60°C
- Isolation: 100% Point-to-Point Isolation
Technical Architecture: Safety and Isolation Integrated
The 1756-OB16IS is engineered for systems where «common ground» failure is not an option. By providing individual isolation for each of its 16 points, it allows for the control of field devices powered by separate, independent power sources. This is particularly vital in safety-critical sectors like oil and gas, power generation, and automotive assembly, where electrical noise or a fault in one safety loop must not compromise the integrity of adjacent loops. When integrated into a GuardLogix system, the 1756-OB16IS supports advanced diagnostic features that ensure the output is in the expected state, providing the deterministic performance required for SIL3 certifications.
Installation Advice: Wiring for SIL3 Compliance
When installing the 1756-OB16IS, wiring discipline is the foundation of system safety. Due to the individual isolation, each output requires a dedicated return wire, meaning you must use the 36-pin 1756-TBCH or 1756-TBS6H terminal block. We recommend using 20 AWG shielded cabling for safety-critical signals to prevent electromagnetic interference. Ensure that the field power supplies are appropriately rated and that the module is configured in Studio 5000 with the correct «Safety» properties. Improper grouping of wires or bypassing individual returns will invalidate the isolated architecture of the module.
Maintenance and Functional Safety Audits
The 1756-OB16IS is a high-reliability component, but functional safety standards require periodic proof testing. Use the Studio 5000 ‘Module Info’ tab to check for any latching faults or backplane communication errors. Since this module often operates in «Energize-to-Safe» or «De-energize-to-Safe» modes, verify the output state during your yearly plant shutdown. Check the front-facing LEDs: a steady green ‘OK’ LED signifies normal operation, while any red flash on the I/O status indicates an individual circuit fault that must be investigated to maintain the safety integrity level (SIL).
FAQs
Q: Can the 1756-OB16IS be used in a standard ControlLogix chassis?
A: Yes, it can function as a high-quality isolated module in standard chassis, though its safety features are fully unlocked when used with a GuardLogix controller.
Q: What is the benefit of individual isolation in safety?
A: It prevents a single power supply fault or ground fault from disabling multiple safety outputs simultaneously.
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