1.Previous
3.Next

Based on that, Modbus defines 3 PDU types:
* MODBUS Request PDU, mb_req_pdu
* MODBUS Response PDU, mb_rsp_pdu
* MODBUS Exception Response PDU, mb_excep_rsp_pdu

:mb_req_pdu = Function code (1 byte) + request data (n bytes)

::request data field's size depends on the function code and usually includes values like variable values, data offset, and sub-function codes.

:mb_rsp_pdu = Function code (1 byte) + response data (n bytes)
::As in mb_req_pdu, response data field's size depends on the function

1.Previous
3.Next