INFICON PSG55x ATM to Medium Vacuum Gauge (Profibus) - Manual (Page 46)

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tira56e1 (2010-02) PxG55x.cp
11 Trip Point Function Block (Relay 1 and 2)
The Trip Point Object models the action of trip points for a device, often corres-
pondding to physical outputs (Discrete Output Object). Each Trip Point channel has
a pointer (Analog Sensor Input Object Instance ID) to a source Analog Sensor
Input Instance.
A trip point value, designated as a High or Low Trip Point, is compared to the spe-
cified instance of an Analog Input Sensor Process Value parameter. This trip point
is intended to be used as a process control indicator only, as distinguished from the
Analog Input Sensor Function Block Object’s Alarm and Warning trip points.
Two different functionalities are implemented: Setpoint function and Atmosphere
(ATM) detection. The functionality of the trip points is set with the parameter
"Setpoint Mode" (ID 202) (
→ 49).
If "Low Trip Enable" (ID 20) is set, "Low Trip Point" is compared to the input value
to generate a trip point condition.
Status will be set if the input (ProcessValue) is at or below the "Low Trip Point". If
the pressure (input) increases above "Low Trip Point + Low Trip Point Hysteresis",
the Status will be reset.
This behavior is similar at the "High Trip Point".
If "High Trip Enable" (ID 18) is set, "High Trip Point" is compared to the input value
to generate a trip point condition.
Status will be set if the input (ProcessValue) is at or above the "High Trip Point". If
the pressure (input) decreases below "High Trip Point - High Trip Point Hysteresis",
the Status will be reset.
This functionality is used to compare the pressure measured by the CDG with the
atmospheric pressure.
The PSG55x and some variants of the PCG55x do not have an Atmos-
phere Pressure Sensor (ATM) and this function (Atmosphere detection)
is not supported.
The parameter "Percentage of ATM" (ID 201) is used to define a value "Percentage
of Atmosphere". This value will be multiplied with the pressure from the Analog
Sensor Instance x (ATM Sensor). Then this result will be copied into parameter
"High Trip Point" or "Low Trip Point", depending on the value of parameter 202
(Setpoint Mode).
Status has the same behavior as in the description of the "Setpoint function".
11.1 Trip Point Function
Block behaviors
11.1.1 Setpoint function
11.1.2 Atmosphere detection