1756-OB8I

The Allen-Bradley 1756-OB8I is a ControlLogix DC isolated output module. It has 8 individually-isolated outputs and has pilot duty available. This module has not been fused and to help protect outputs, using a fused IFM is recommended.

A 36-pin removable terminal block housing, or RTB, is needed before you can install the 1756-OB8I module in a compatible chassis. For this module, you can only use a 1756-TBCH or 1756-TBS6H RTB. Remember to ground and install the chassis before installing the module with the RTB.

The communication formats that are available to the 1756-OB8I module are Listen-Only Rack Optimization, Listen-Only Output Data, Scheduled Output Data, Output Data, and Rack Optimization. The module also has a feature that allows you to change states in Fault or Program mode per point and the available options are On, Off, and Hold Last State, with 'Off' set as the default option.

The 1756-OB8I module is a 12/24 volts DC source module with an operating voltage range between 10 and 30 volts DC. Its total backplane power is 0.89W and the current draw of 165 mA at 5.1 volts and 2 mA at 24 volts. Its surge current is 4 A for 10 ms each point, which is repeatable every second at 140 Degrees Fahrenheit. It also has a minimum load current of 2 mA, a maximum current per point of 140 Degrees Fahrenheit, and a maximum current per module of 16 A at 140 Degrees Fahrenheit. The module’s maximum on-state voltage drop is 0.5 volts DC at 2 A and a maximum off-state leakage current of 0.5 mA per point.

Its maximum power dissipation of 4.6W at 140 Degrees Fahrenheit and a thermal dissipation of 15.70 BTU/hr. The module has been routine tested at 1350 volts AC for 2 s and has a continuous isolation voltage of 250 volts.