
16
6
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F
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.
Table 6.1 Exception Response Codes
6.1
Examples
A read register request to read holding register address 91 of slave 01 (undefined address for slave, beyond address limit) is
shown below.
The response is an exception response sighting ‘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.