Allen Bradley1756-OB16EControlLogix 16-Point DC Digital Output Module, 10–31.2 V DC Sourcing, Electronically Fused

Product Description

What this part is

An Allen-Bradley ControlLogix 1756-series digital output module carrying 16 solid-state DC outputs. The outputs are sourcing, working over a 10 to 31.2 V DC range, and are arranged as two electrically isolated groups of eight so that two separate 24 V field supplies or two separate machine sections can be served from one slot. Every output is electronically fused rather than protected by a replaceable cartridge fuse. The module occupies one slot in a 1756 ControlLogix chassis and communicates with the controller across the chassis backplane.

Decoding the catalogue number

1756 is the ControlLogix I/O and chassis platform. O marks an output module, B the DC voltage category, and 16 the point count. The trailing E is the significant letter: it denotes the electronically fused version. In the same family, a trailing D as in 1756-OB16D is the diagnostic version, which reports field faults such as no-load and short-circuit conditions per point and carries a higher 2 A per-point rating; a plain 1756-OB16 has neither electronic fusing nor diagnostics. SER A is the module series letter, which tracks hardware revision rather than function.

What these specs mean in practice

The per-point figure is 1 A at 60 °C, with 8 A the ceiling for the module as a whole, so the honest design limit is the module total rather than sixteen times the per-point number. That total is what decides whether a bank of solenoid valves fits in one slot. Electronic fusing trips and reports in firmware instead of requiring a fuse change, which shortens a fault-clear to an operator reset — but it responds to inrush as well as to steady-state current, so large safety contactors and heavily inductive loads can trip a channel whose running current sits well inside specification. Interposing relays are the usual answer for those loads. The 1 ms output delay is fast enough that switching timing is set by the program scan rather than by the module.

Quantity and configuration

1 Pc. Module only. No removable terminal block, no chassis, no power supply, no wiring arm and no field 24 V supply. The RTB for this module is a separate 1756-TBNH or 1756-TBCH item.

Installation and setup notes

The module is inserted into any I/O slot of a 1756 chassis; slot position is arbitrary but must match the module’s entry in the controller’s I/O configuration tree, since ControlLogix identifies modules by slot, catalogue number and revision. Electronic keying settings decide whether a differing series or revision is accepted on replacement. Field wiring lands on the removable terminal block, so a module swap does not disturb the wiring.

Interchange guidance

Later series letters of 1756-OB16E are the substitution path and take the same terminal block. The 1756-OB16D is a related module rather than a replacement: it doubles the per-point current and adds per-point diagnostics, which changes both the tag structure in the program and the module profile. The 1756-OB16I is an individually isolated version with a different group arrangement, and 1756-OB8, 1756-OB32 and similar are different point counts. Sinking DC output modules in the same range are not interchangeable with a sourcing module on existing field wiring, since the common rail polarity differs.