A broad range of wireless transmitters are available for continuous measurements, such as pressure, temperature, flow and level, as well as analytical measurements such as pH. Wireless discrete transmitters are also available that may be used to monitor the state of a process operation. Based on the broadening acceptance of wireless transmitters, manufacturers have developed and introduced wireless actuators for on/off valves. Wireless adaptors are also available that enable control to be implemented with throttling valves equipped with digital valve positioners. Using this capability, continuous and discrete control may be addressed using wireless transmitters and wireless valves.
When using wireless transmitters in control applications, it's necessary to structure the control in a manner that compensates for non-continuous measurement updates. One way to do this is to use the approach called PIDPlus. Similarly, when using a wireless valve, the control must be structured to account for variable delays that may be introduced by wireless communications to the valve. Fortunately, technical solutions exist that enable wireless transmitters and/or wireless valves to be successfully used in closed-loop control applications.