Because Modbus does not specify which specific function codes are necessary in a device (much less the data group types needed), devices from different vendors tend to greatly vary. In addition, the data format of register-held data, as previously mentioned, is left up to the vendor. Quite commonly, different byte-order storage schemes are used for storing 32-bit data types such as float and long (integer).

With this in mind, the client networks (ModbusAsyncNetwork, ModbusTCPNetwork, and ModbusTCPGateway) provide four configuration properties, set at the network-level, that act as “global” Modbus defaults for all devices on the associated network. If needed, any (or all) of these settings can be overridden at the device-level (see Device-level Modbus Config properties). Properties are: