Allen-Bradley MediaChecker 1788-MCHKR Manual page 15

Twisted Pair Cable Test Results
Important: If you suspect inaccurate length readings,
calibrate the MediaChecker to the cable. See
"Calibrating the MediaChecker to a Cable" on
page 10.
Length measurements show the total length
of the trunk plus all drops on the cable. For
information on calculating the length of just
the trunk, drops, or taps, see "Calculating
Trunk, Drop, or Tap Lengths" on page 29.
Twisted pair cables include DeviceNet, DH+/RIO, and
Ethernet. When you test twisted pair cables, the
MediaChecker checks for the Cable ID at the other end of
the cable and displays one of the following when a pass
condition exists:
aan09f.eps
"PASS" means the cable is
good. "RA" means the Cable
ID is detected.
The Test Function (TEST)
aan59f.eps
Tables 8 and 9 show examples of DeviceNet cable
failures with and without the Cable ID connected.
DH+/RIO and Ethernet displays use the same fault
indicators, but show different symbols for the wires. (See
Table 6.)
Important: The MediaChecker may not detect the Cable
ID under some open and short conditions. The
MediaChecker alternately displays "??" and
"RA" (for "Resistive Adapter") when the Cable
ID is detected but a problem with the cable or
the Cable ID is interfering with the identification
process.
"--" means the Cable ID is not
detected. If the MediaChecker
does not detect a properly
connected Cable ID, the cable
is probably defective (most
likely at the far end).
1788-UM002A-US-P – April 2000
15