Purchase now: Allen-Bradley 1756-OB16I ControlLogix Isolated DC Module
Atlantechdrives provides you the 1756-OB16I, an advanced 16-point DC sourcing output module featuring individual point-to-point isolation. This «I» version is specifically engineered for complex industrial systems where multiple DC power sources or different voltage potentials must be managed by a single module without electrical interference between channels.
- Outputs: 16 Individually Isolated points
- Voltage Range: 10-30V DC
- Isolation: 100% Point-to-Point (No common ground)
- Current Rating: 0.5A per point @ 60°C
- RTB Required: 1756-TBCH or 1756-TBS6H (36-pin)
Technical Superiority: Individual Point Isolation
The 1756-OB16I stands out in the ControlLogix lineup because it removes the «Common» connection limitation. Each of the 16 outputs is electrically independent, allowing you to control loads that are powered by separate battery banks, isolated power supplies, or even different DC voltage levels (e.g., mixing 12V and 24V signals on the same module). This architecture is critical in substation automation, marine applications, and large-scale process plants where ground loops can cause devastating signal noise or equipment damage. By isolating each point, the 1756-OB16I ensures that a fault on one circuit remains localized and does not affect the operation of the other 15 channels.
Installation Advice: Managing 36-Pin Wiring
Due to the individual isolation, the 1756-OB16I requires two wires for every point (a source and a return), necessitating the use of the 36-pin 1756-TBCH terminal block. Wiring 32 separate conductors into a single module slot can be challenging; we recommend using 22 AWG wire with thin insulation to ensure the terminal block cover can close properly. Labeling each pair is essential for future troubleshooting. Ensure that the «Module Keying» in Studio 5000 is set to «Electronic Keying» or «Exact Match» to prevent the accidental insertion of a non-isolated module into a wired isolated base, which could cause a short circuit across power sources.
Maintenance and Environmental Reliability
The 1756-OB16I generates slightly more heat than standard modules due to the additional isolation components. Maintenance should include an annual check of the terminal block connections for tightness, as thermal cycling in industrial cabinets can loosen screw terminals over time. Check the 4-character status display for any «I/O Fault» messages. Because there are no shared commons, troubleshooting is simplified: you can use a voltmeter on any individual pair without worrying about back-feeding through a shared ground rail, making the 1756-OB16I one of the safest modules for live-panel diagnostics.
FAQs
Q: Can I mix different DC voltages on the 1756-OB16I?
A: Yes, because each point is individually isolated, you can mix different DC potentials as long as they are within the 10-30V DC range.
Q: Does it support sinking or sourcing?
A: The 1756-OB16I is a sourcing module, meaning it provides the positive leg of the DC circuit to the load.
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