Diagnose Common Problems - Parker H Series Installation & Service Instructions Manual

Diagnose Common
Problems
problem
common mode problems
bus errors
Use the following tips to diagnose and correct some of the most commonly
occurring network problems.
TIP
symptom
• nodes near the end of the trunk line stop
communicating after operating normally
• the network communicates only when the
number of nodes is decreased or the trunk
length is reduced
• properly configured slave devices are not
detected by the scanner
• node operates intermittently (drops off
suddenly and unexpectedly)
• LEDs or other displays indicate buss off
errors
Correct and Prevent Network Problems
Most devices have some type of status display, such as
LEDs or alpha-numeric message displays. If any of your
devices display error messages, refer to the documentation
provided by the manufacturer to interpret the error codes.
do this
• check communications at the end of the
network
• check common mode voltage
• move nodes from the overloaded section to
the less-overloaded section
• shorten the overall length of the network
cable
• move power supply in the direction of the
overloaded section of the network
• move high-current nodes (e.g., valve banks)
close to the power supply
• add a second power supply
• break the network into 2 separate networks
• Check that baud rates are set correctly. A
device with an incorrectly set baud rate
affects other nodes when the device
attempts to go online.
• replace the suspected faulty device and
re-check error rates
• check cables for intermittent operation by
shaking, bending or twisting the suspected
cable or connection and checking error rates
Publication DNET-UM072C-EN-P - July 2004
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