ICP DAS USA ET-7H16M Series User Manual page 81

A.3. Data Field
The data field consists of messages sent between master and slave. The messages contain
additional information about the action to be taken by the slave or any information requested by
the slave. When the slave does not require this information the data field can be nonexistent.
A.4. Error Check
The error check performed in Modbus/RTU is Cyclic Redundancy Check (CRC). Both the
transmitting device and the receiver compute CRC. Two bytes are used for this purpose and
generally one bit errors are detected by this method.
PET-7H16M Series User Manual, version 1.0.1 P.81