A slave-type Modbus network allows the station to appear as one or more “virtual” Modbus slave devices, each providing some number of Modbus “virtual” data items. On the Modbus network the station simply waits for (and responds to) client requests from a master device. All proxy points are Modbus “server” types, where point polling monitors for external writes to some proxy points. Data exchange with the Modbus master occurs in this fashion with proxy points, and in rare cases with reads and writes to server file records (for string data).

See the following sections: