Model 3095FB Multivariable Transmitter with Modbus Protocol
Modbus Protocol Guide
Page 15 of 79
2.5 Exception Responses
If the transmitter cannot execute a command issued by a query, the most significant bit in the
response function field is set, and the data field contains an exception response, which
explains why the transmitter cannot execute the command.
If the transmitter receives a query that will take over 250 ms it will respond with the normal
reply even though the command has not completed. Any subsequent query from the host will
result in a Slave Busy (06) response until the first command finishes processing.
query $45 start reg H start reg L reg pair
cnt H
reg pair
cnt L
...
resp $45 byte cnt data H data L ...
resp $C5 error code
query $46 start reg H start reg L reg cnt H reg cnt L byte cnt data H data L ...
resp $46 start reg H start reg L reg pair
cnt H
reg pair
cnt L
resp $C6 error code
Table 2-5 Exception Responses
Exception
Response
Description Explanation of Exception Response
01 Illegal function The received message function is not an allowable
action for the transmitter
02 Illegal data address The address referenced in the data field is not an
allowable address for the memory location
03 Illegal data value The value referenced in the data field is not
allowed in the addressed memory location
04 Slave Device Failure An unrecoverable error occurred while the slave
was attempting to perform the requested action.
06 Slave device is busy The slave is engaged in processing a long duration
command. The host should retransmit the mes-
sage later when the slave is free.
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