INFICON BCG450-SD ATM to Ultra-High Vacuum Triple Gauge (DeviceNet) User Manual
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tira40e1 (2005-04) BCG450SDv1.cp
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A bit mapped byte which indicates the Alarm and Warning Exception status of the
object instance. The following definition applies:
Bit
Definition
0
High Alarm Exception:
0 = cleared
1 = set
1
Low Alarm Exception:
0 = cleared
1 = set
2
High Warning Exception: 0 = cleared
1 = set
3
Low Warning Exception:
0 = cleared
1 = set
4
Reserved
5
Reserved
6
Reserved
7
Reserved
If the pressure (attribute 6, instance 1 and 2) decreases below the Setpoint value
(attribute 6, instance 21 and 22) an alarm or warning exception condition will be
generated. The hysteresis is set to 10%.
For example: A Set Point value of 100 will result in an exception condition being set
when the Value is below 100 and cleared when the Value increases above 110.
The setpoints can only be read by DeviceNet. It is not possible to set the
values or to influence the state of the relays by DeviceNet. Even if the de-
vice is not allocated, the relay status is set corresponding to the voltage ad-
justed by the two setpoint potentiometers.
Only in case of a microcontroller RESET (for example reset on Identity Ob-
ject), the relays will be reset too.
The setpoint is available in the actual pressure unit and data type. If the pressure
unit "Counts" is set, use the following formula for the conversion from Counts to
pressure:
p
mbar
=
10
Counts / 2000 - k
where:
k
mbar
=
12.5
k
Torr
=
12.624903
k
Pa
=
10.5
The relation between setpoint and voltage is:
p
mbar
=
10
(U - 7.75) / 0.75 + c
where:
c
mbar
=
0
c
Torr
=
-0.125
c
Pa
=
2
The setpoints are only activated, if the pressure is below 100 mbar, therefore a
setpoint above 100 mbar can not be realised.
Status
Setpoints