Endress+Hauser RIA15 - Device Variables for Multivariable Devices

HART
®
communication
RIA15
62 Endress+Hauser
15.6 Device variables for multivariable devices
Multivariable measuring devices can transmit up to four device variables via HART
®
: the
Primary Variable (PV), Secondary Variable (SV), Tertiary Variable (TV) and Quaternary
Variable (QV).
Below you will find some examples of what default values can be set for these variables for
various sensors/actors:
Flowmeter, e.g. Promass:
• Primary process variable (PV) -> Mass flow
• Secondary process variable (SV) -> Totalizer 1
• Third process variable (TV) -> Density
• Fourth process variable (QV) -> Temperature
Temperature transmitter, e.g. TMT82:
• Primary process variable (PV) -> Sensor 1
• Secondary process variable (SV) -> Device temperature
• Third process variable (TV) -> Sensor 1
• Fourth process variable (QV) -> Sensor 1
For a level measuring device such as the Levelflex FMP5x, these four values can be as
follows:
Level measurement:
• Primary process variable (PV) → Level linearized
• Secondary process variable (SV) → Distance
• Third process variable (TV) → Absolute echo amplitude
• Fourth process variable (QV) → Relative echo amplitude
Interface measurement:
• Primary process variable (PV) → Interface
• Secondary process variable (SV) → Level linearized
• Third process variable (TV) → Upper interface thickness
• Fourth process variable (QV) → Relative interface amplitude
HART
®
actor, e.g. positioner:
• Primary process variable (PV) -> Actuating value
• Secondary process variable (SV) -> Valve set point
• Third process variable (TV) -> Target position
• Fourth process variable (QV) -> Valve position