Elpro's I/O expansion products do not have an integral radio and are designed to expand I/O capability of Elpro's multi I/O, gateway and modem products.
Connected via RS485, Elpro's 115S series expansion products offer multiple I/O channel combinations with multiple 115S expansion products able to be connected to a single radio device (e.g. multi I/O, Ethernet modem, etc.)
In practice, Elpro's I/O expansion modules communicate either Modbus RTU or Elpro protocol and can also function as stand alone Modbus I/O (serial multiplexer units).