Rockwell Automation 1788 NetLinx Media Checker Users Manual - Manual (Page 21)

The Test Function (TEST) 21
1788-UM002A-US-P – April 2000
Coaxial 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 taps 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 or
refer to the Quick Reference Card.
When you test coaxial cables (ControlNet) with a
terminating resistor connected, the MediaChecker sounds
three short tones and displays the total resistance of the
terminator and cable wires:
aan10f.eps
Important: Coaxial cables must be unterminated for the
MediaChecker to display the cable’s length.
An open in a coaxial cable looks just like an
unterminated cable. If you know the cable
is longer than the measurement shows,
there is probably an open on the cable.
The MediaChecker sounds three short tones and displays
“FAIL” if a failure is detected.
Additional information about a failure is printed on the
second line of the display and if the
] symbol is
displayed, additional information can be viewed with the
D C
keys.
Table 10 shows examples of ControlNet cable failures.