Of Operation 2

Parallel Device Capacitance
The summation of the capacitance values of all connected devices in a network

Parallel Device Resistance
The parallel combination of the resistance values of all connected devices in the network; typically, there is only one low-impedance device in the network, which dominates the parallel device-resistance value

Passthrough
A feature of some systems that allows HART protocol send-and-receive messages to be communicated through the system interface

PID Proportional-integral-derivative

PID Control
Proportional-plus-integral-plus-derivative control; used in processes where the controlled variable is affected by long lag times

Point-to-Point
A HART protocol communication mode that uses the conventional 4–20mA signal for analog transmission, while measurement, adjustment, and equipment data are transferred digitally; only two communicating devices are connected together

Polling
A method of sequentially observing each field device on a network to determine if the device is ready to send data

Polling Address
Every HART device has a polling address; address 0 is used for
point-to-point networks; addresses 1–15 are used in multidrop networks

Process Variable
A process parameter that is being measured or controlled (e.g., level, flow, temperature, mass, density, etc.)