搬自http://code.google.com/p/nmodbus，适合.Net3.5//AC#implementationoftheModbusprotocol.ProvidesconnectivitytoModbusslavecompatibledevicesandapplications.SupportsserialASCII,serialRTU,serialoverUSBASCII,serialoverUSBRTU,TCP,andUDPprotocols.