Rockwell Automation 1756-XXXX ControlLogix Digital I/O Modules - Manual (Page 73)

Rockwell Automation Publication 1756-UM058G-EN-P - November 2012 73
Diagnostic Module Features Chapter 4
Open Wire Detection
Open Wire is used to verify the field wiring is connected to the module. The field
device must provide a minimum leakage current to function properly.
A leakage resistor must be placed across the contacts of an input device. The
resulting current is then expected to exist when the input is open. For more
information, see each module’s specifications in
Chapter 8 .
When an Open Wire condition is detected, a point-level fault is sent to the
controller to identify the exact point fault. This feature has a corresponding tag
that can be examined in the user program in the event of a fault.
Follow these steps to configure open wire detection.
1. On the Module Properties dialog box, click the Configuration tab.
2. Do one of the following in the Open Wire (middle) column:
•
To enable the open wire detection for a specific point, check the
corresponding checkbox.
• To disable open wire detection for a specific point, clear the
corresponding checkbox.
3. Click OK.