Rockwell-automation 1788 NetLinx Media Checker Users Manual Bedienungsanleitung PDF herunterladen (Seite 18)

The Test Function (TEST)

1788-UM002A-US-P – April 2000

Table 9. DeviceNet Test Failures (without Cable ID)

Display Failure Description

The MediaChecker detects a

very high resistance between the

data lines and the “-” power line.

“FAULT” and “350Ω“ are blinking. There is probably

one or more I/O device connected to the cable under

test. To determine the cable length, do one of the

following:

• Disconnect the I/O devices and retest the cable.

• Install a terminator at the far end of the cable,

measure the resistance of the cable in series with

the terminator; then calculate the cable length. See

“Calculating the Distance to a Short” on page 32.

The MediaChecker detects a

fairly high resistance between

the CAN_H and CAN_L (data)

wires.

“FAULT” and “OPEN” are blinking.*

A terminator is probably connected to one end of the

bus. You can subtract the resistance of the terminator

(typically 120 Ω) from the measured resistance, then

calculate an approximate length using the remaining

resistance. See “Calculating the Distance to a Short”

on page 32.

To determine the cable’s wire map and get a more

accurate length measurement, replace the terminator

with the Cable ID and run the test again.

* Because some measurements are not possible on faulted cables, the MediaChecker might report the + and – wires as open when they

are not actually open.

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Rockwell-automation 1788 NetLinx Media Checker Users Manual Bedienungsanleitung Seite 18