Rockwell Automation 1788 NetLinx Media Checker Users Manual - Manual (Page 20)

20 The Test Function (TEST)
1788-UM002A-US-P – April 2000
Table 9. DeviceNet Test Failures (without Cable ID) (cont.)
Display Failure Description
The MediaChecker measures a
very short length for the CAN_L
wire as compared to the other
wires. “OPEN” is blinking.* The L wire is open at the near end.
To detect an open at the far end, connect the Cable ID
to the far end and repeat the test or connect the Cable
ID to this end of the cable and repeat the test from the
other end.
* Because some measurements are not possible on faulted cables, the MediaChecker might report the + and – wires as open when they
are not actually open.