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ROC827 Instruction Manual
Issued Mar-06 Glossary A-6
P, Q (continued)
P/DP
Pressure/Differential Pressure.
PI
Pulse Input.
PID
Proportional, Integral, and Derivative control feedback action.
PIT
Periodic Timer Interrupt.
PLC
Programmable Logic Controller.
Point
Software-oriented term for an I/O channel or some other function, such as a flow
calculation. Points are defined by a collection of parameters.
Point Number
The physical location of an I/O point (module slot and channel) as installed in the ROC.
Point Type
Defines the database point to be a specific type of point available to the system. The
point type determines the basic functions of a point.
Preset
Number value previously determined for a register.
PRI
Primary PID control loop.
Protocol
A set of standards that enables communication or file transfers between two computers.
Protocol parameters include baud rate, parity, data bits, stop bit, and the type of duplex.
PSTN
Public Switched Telephone Network.
PT
Process Temperature.
PTT
Push-to-Talk signal.
Pulse
Transient variation of a signal whose value is normally constant.
Pulse Interface
module
A module that provides line pressure, auxiliary pressure, and pulse counts to a ROC.
PV
Process Variable or Process Value.
R
Rack
A row of slots on a ROC into which I/O modules can be plugged. Racks are given a letter
to physically identify the location of an I/O channel (such as “A” for the first rack). Built-in
I/O channels are assigned a rack identifier of “A” while diagnostic I/O channels are
considered to be in “E” rack.
RAM
Random Access Memory. RAM is used to store history, data, most user programs, and
additional configuration data.
RBX
Report-by-exception. RBX always refers to Spontaneous RBX in which the ROC contacts
the host to report an alarm condition.
RR
Results Register; stores the Signal Value Analog (SVA).
RFI
Radio Frequency Interference.
RI
Ring Indicator modem communications signal.
ROC
Remote Operations Controller microprocessor-based unit that provides remote
monitoring and control.
ROCLINK 800
Microsoft® Windows®-based software used to configure functionality in ROC units.
ROM
Read-only memory. Typically used to store firmware. Flash memory.
Rotary Meter
A positive displacement meter used to measure flow rate, also known as a Roots meter.
RTC
Real-Time Clock.
RTD
Resistance Temperature Detector.
RTS
Ready to Send modem communications signal.
RTU
Remote Terminal Unit.
RTV
Room Temperature Vulcanizing, typically a sealant or caulk such as silicon rubber.