INFICON BCG450-SD ATM to Ultra-High Vacuum Triple Gauge (DeviceNet) - Manual (Page 17)

tira40e1 (2005-04) BCG450SDv1.cp
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Assemblies or connections may produce this class-level attribute, instead of the
Value (Attribute ID 6) of the active S-Analog Sensor instance. The S-Analog Sen-
sor class-level attribute Active Instance Number identifies the object instance that is
currently active and providing the Value to the Active Value class-level attribute
which is, in turn, produced by the input assemblies that have Active Value as a
member.
The device internally modifies this attribute, as required, to identify the S-Analog
Sensor object instance providing the Value member which is copied into the Active
Value for all Input Assemblies and the Alarm/Warning Exception Details for the
S-Device Supervisor object.
The Active Instance Number will be modified based upon the Active Value in order
that the best gauge, corresponding to a given S-Analog Sensor instance, will be
active for the given measurement range.
This attribute is used to determine the size of all Input Assemblies within a node.
Because the gauge has three different measurement principles (Pirani, capacitance
diaphragm gauge, hot ionization gauge) this attribute is supported to give you the
information whether the gauge is outside the specified measurement range.
Gauge exposed to
pressure range
Class Level Status Extension
5
×10 -10 … 1500 mbar all bits set to "0"
>1500 mbar bits "Reading Invalid" and "Overrange Exceeded" set
<5
×10 -10
mbar bits "Reading Invalid" and "Underrange Exceeded" set
The Class Level Status Extension attribute is mapped to the Device Exception
Detail Warning Byte 0 of the Device Supervisor Object.
Three S-Analog Sensor Instances (Instance 1, Instance 2, Instance 21 and In-
stance 22) are available. Instance 1 represents the physical sensor reading of the
heat transfer vacuum gauge (pressure), Instance 2 represents the physical sensor
reading of the hot cathode ion gauge (pressure).
Instance 21 and Instance 22 represent the value of the Setpoint A and Setpoint B.
Following is the Instance 1 with the subclass extension of the heat transfer vac-
uum gauge (pirani gauge) part of the BCG450-SD. This instance is used to pro-
vide control and status information for the Pirani gauge part of the BCG450-SD.
Attribute
ID
Access Rule NV/
V
Name DeviceNet Data
Type Description of
Attribute Semantics of Values
3 Set /Cond.
→ below
NV Data Type USINT Determines the
Data Type of Value
and all related
attributes as speci-
fied in this table. → "Semantics" section below.
Int
C3
h
[default]
float
CA
h
4 Set
→ below
NV Data Units UINT Determines the
Units context of
Value and all re-
lated attributes. Supported Values:
Counts
1001
h
[default]
mbar
1308
h
Torr
1301
h
Pascal
1309
h
5 Get V Reading Valid BOOL Indicates that the
Value attribute
contains a valid
value. 0 = invalid
1 = valid
(invalid: e.g., not warmed up
yet)
6 Get V Value INT or specified
by Data Type Analog input value The corrected, converted, cali-
brated final value of the sensor.
→ "Semantics" section below.
Active Value
Active Instance Number
Number of Gauges
Class Level Status
Extension
2.4.2 Instance Attributes
2.4.2.1 Instance Attributes of
Instance 1 /
Pirani Instance