The InstaLink®-CMM module was designed with process automation in mind. In applications with critical control loops the CMM module provides a continuous indication that the loop integrity is intact regardless of the status of the field device or the PLC/DCS digital output.
The user configures the module for use with either digital inputs or digital outputs. Configuration is via a jumper on the module. A small leakage current is introduced into the loop and is monitored to verify continuity in the loop. Two status LEDs are included, one to indicate 24Vdc is present (the power supply is on and the fuse is good) and the other to indicate continuity (LED on means continuity in loop). The modules digital output is active when the loop continuity is intact.
Like most other InstaLink® modules provision is made to jumper the 24Vdc power to adjacent modules. Jumpers are included with each module.