17
Table 6.1 Exception Response Codes
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6
EXCEPTION RESPONSES
The exception response codes sent by the slave are shown in Table 6.1. When a slave detects one
of these errors, it sends a response message to the master consisting of slave address, function
code, error code and error check fields.
6.1
Examples
A Read Register Request to read holding register address 300 of Slave 01 (undefined address for
Slave, beyond address limit).
The slave replies with an exception response signifying an ‘illegal data address’. To indicate that the
response is a notification of an error, the most significant bit of the function code is set to 1.
