The RAD-900-DAIO6, a 900-MHz outdoor Radioline spread-spectrum transceiver, facilitates retrofit and expansion projects by eliminating or supplementing signal wiring for conventional I/O signals. This device can monitor digital on/off status, actuate relay outputs and transmit or receive 4–20 mA signals over distances as far as 20 miles. The I/O signals can be mirrored at other stations in the wireless network or mapped to Modbus RTU for easy integration into a Modbus host system. A single network can support as many as 250 radios with any combination of repeaters and slaves, and the transmitter is completely interoperable with the existing Radioline products.