158 ACS550 User’s Manual
Embedded Fieldbus
Diagnostic Situations
The sub-sections below describe various diagnostic situations – the problem
symptoms and corrective actions.
Normal Operation
During normal network operation, 5306…5309 parameter values act as follows at
each drive:
• 5306 EFB OK MESSAGES advances (advances for each message properly received
and addressed to this drive).
• 5307 EFB CRC ERRORS does not advance at all (advances when an invalid
message CRC is received).
• 5308 EFB UART ERRORS does not advance at all (advances when character format
errors are detected, such as parity or framing errors).
• 5309 EFB status value varies depending on network traffic.
Loss of Communication
The ACS550 behavior, if communication is lost, was configured earlier in
"Communication Fault". The parameters are 3018
COMM FAULT FUNC and 3019 COMM
FAULT TIME. The "Complete Parameter Descriptions" section describes these
parameters in detail.
No Master Station on Line
If no master station is on line: Neither the EFB OK MESSAGES nor the errors (5307 EFB
CRC ERRORS and 5308 EFB UART ERRORS) increase on any of the stations.
To correct:
• Check that a network master is connected and properly programmed on the
network.
• Verify that the cable is connected, and is not cut or short circuited.
Duplicate Stations
If two or more stations have duplicate numbers:
• Two or more drives cannot be addressed.
• Every time there is a read or write to one particular station, the value for 5307 EFB
CRC ERRORS or 5308 EFB UART ERRORS advances.
To correct: Verify the station numbers of all stations. Change conflicting station
numbers.
Swapped Wires
If the communication wires are swapped (terminal A on one drive is connected to
terminal B on another):
• The value of 5306 EFB OK MESSAGES does not advance.
• The values of 5307 EFB CRC ERRORS and 5308 EFB UART ERRORS are advancing.
To correct: Check that the RS-485 lines are not swapped.
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