Glossary of Terms
G-6 Rev 2/01
R
Rack — For a ROC, a rack is a row of slots into which I/O modules may be plugged. The rack is
given a letter to physically identify an I/O channel location, 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 rack “E”.
RAM — Random Access Memory. In a ROC or flow computer, it is used to store history, data, most
user programs, and additional configuration data.
RBX — Report-by-exception. In a ROC or flow computer, it always refers to spontaneous RBX in
which the field device contacts the host to report an alarm condition.
RFI — Radio frequency interference.
RI — Ring Indicator modem communications signal.
ROC — Remote Operations Controller, Fisher Control’s microprocessor-based unit that provides
remote monitoring and control.
ROCLINK — Configuration software used to configure Fisher ROCs or flow computers to gather
data, as well as most other functions.
ROM — Read-only memory. Typically used to store firmware. Flash memory.
RTC — Real-time clock.
RTD — Resistance Temperature Detector.
RTS — Ready to Send modem communications signal.
RTU — Remote Terminal Unit (or Remote Telemetry Unit).
RX or RXD — Received Data communications signal.
S
SAMA — Scientific Apparatus Maker’s Association.
Soft Points — A type of ROC point with generic parameters that can be configured to hold data as
desired by the user.
SP — Static Pressure, or Setpoint.
SPI — Slow Pulse Input.
SPK — Speaker.
SRAM — Static Random Access Memory. Stores data as long as power is applied; typically backed
up by a lithium battery or supercapacitor.
SVA — Signal Value Analog.
SVD — Signal Value Discrete.
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