INFICON SKY CDGxxxD (DeviceNet) - Manual (Page 28)

28
tira51e1 (2009-01) CDGxxxD.cp
If "Low Trip Enable" is set, the setpoint function is used (automatically attr. 101 is
set to zero and the functionality ATM detection is disabled).
Low trip point is compared to the input value to generate a trip point condition.
Status will be set if the input value is at or below the low trip point.
If the pressure increases above the low trip point and hysteresis, the status will be
reset.
This functionality is used to compare the pressure measured by the CDG with the
atmospheric pressure.
Attribute 101 is used to define a value "Percentage of Atmosphere". This value will
be multiplied with the pressure from the S-Analog sensor instance 2 (ATM sensor).
Then the result will be copied into attr. 102 = ATM high trip point. If a value is
written to percentage of atmosphere, the low trip enable is set to zero.
Status will be set if the input value is at or above the high trip point.
If the pressure decreases below the high trip point - hysteresis, the status will be
reset.
The Hysteresis value specifies the amount by which the Input value must transition
in order to clear a trip point condition.
The following relationship demonstrates the logic for a Low Trip Point:
For Status not set:
If (Input ≤ Trip Point Low)
Then set Status
For Status set: If (Input > Trip Point Low +Hysteresis)
Then clear Status
The trip point object provides the following common services:
Service
code
Service name Description of service
0E
h
Get_Attribute_Single Returns the contents of the specified attribute.
10
h
Set_Attribute_Single Modifies an attribute value.
4.5.3 Semantics
Setpoint function
ATM detection
Hysteresis
4.5.4 Common Services