Communications
11.7 Error Handling
BW500 and BW500/L
150 Operating Instructions, 12/2016, A5E33482052-AD
BW500 and BW500/L uses the following exception codes:
01 Illegal Function The function code received in
the query is not an allowable
02 Illegal Data Address The data address received in
the query is not an allowable
03 Illegal Data Value A value contained in the query
data filed is not an allowable
04 Slave Device Failure
An unrecoverable error occurred
while the slave was attempting
to perform the requested action.
05 Acknowledge The slave has accepted a re-
quest and is processing it, but a
long duration of time is required.
06 Slave Device Busy The slave is processing a long-
duration program command.
08 Memory Parity Error The slave attempted to read
extended memory, but detected
a parity error in the memory.
Service may be required on the
Errors can be divided up into two general sources:
● an error in transmission
● user tries to do something that is not a valid action
In the first case, the BW500 and BW500/L will not respond and let the master wait for a
‘response time out’ error, which will cause the master to re-send the message.
In the second case, it depends on what the user tries to do. Listed below are various actions and
what the expected outcome is. In general, BW500 and BW500/L will not give an error to the user
request.
● If the user reads an invalid parameter, the user will get a number back.
● If the user writes an invalid parameter (a non-existing parameter or a read only parameter),
the value will be ignored and no error response will be made. However, the current value will
not reflect the desired new value.
● If the user writes a read only register, then the value will be ignored and no error response
will be made. However, the current value will not reflect the desired new value.
● If the user attempts to write one or more registers that are out of range, an exception
response code 2 will be generated.
● If using an unsupported function code, undocumented results may occur. The user is
encouraged not to do this.
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