yan
$ nosetests –nocapture -v mytest.py
SymPy http://docs.sympy.org/latest/tutorial/basic_operations.html
http://www.electroind.com/pdf/Modbus_messaging_on_TCPIP_implementation_guide_V11.pdf
PDU (Protocol Data Unit)
Function Code | Data
ADU (Application Data Unit) (8 bytes)
Additional address | PDU | Error Check (CRC16(PDU))
MODBUS TCP/IP ADU (12 bytes)
MBAP Header | PDU