Wireless Transmitters connect directly to sensor and control signals, and transmit the signal values by radio. The signals are either recreated as similar signals or output as a data connection - Ethernet, Profibus, Modbus etc.
Wireless networks can be as simple as two units transferring a small number of signals from one point to another, or they can be complex data-acquisition networks with multiple "master" interfaces to external systems.
ELPRO I/O Products
Honeywell Transmitters