Modbus RTU Master

The part supplementary data of error messages of Modbus master driver may contain following data:

•	CRC are the received CRC bytes in hexadecimal format

•	data_address is the start address of data accessed by the request in the Modbus address notation

•	data_size is the size of data accessed by the request expressed like a number of data elements in decimal format.

•	direction (from the point of view of the terminal) is:

- "rcv" for transmitting data from the slave to the master

- "snd" for transmitting data from the master to the slave

•	exception_code is the exception response code in hexadecimal format

•	station is the decimal station number of the accessed slave

The Modbus Modicon and Modbus general address notations are like this:

- <address_type> <address>

•	address_type may be one of:

- 0,O,M

- 1,I

- 3

- 4,R

•	address is an unsigned number in decimal format

The Modbus ABB address notation is like this:

- <address_type> <group>,<channel>

•	address_type may be one of: E, A, M, EW, AW, MW, KW, MD, KD

•	group is an unsigned number in decimal format

•	channel is an unsigned number in decimal format