INFICON HPG400 ATM to High-Vacuum Gauge User Manual
Page 29
tina31e1 (2004-05) HPG400 v1.om
29
Bit 1
Bit 0
Definition
0
0
Emission off
0
1
Emission on
Bit 2
Definition
0
1000 mbar adjustment off
1
1000 mbar adjustment on
Bit 3
Definition
0
⇔ 1
Toggle bit, changes with every
string received correctly
Bit 5
Bit 4
Definition
0
0
Current pressure unit mbar
0
1
Current pressure unit Torr
1
0
Current pressure unit Pa
Bit 7
Bit 6
Definition
x
x
Not used
Bit 3
Bit 2
Bit 1
Bit 0
Definition
x
x
x
x
Not used
Bit 7
Bit 6
Bit 5
Bit 4
Definition
0
1
0
1
Pirani adjusted poorly
1
0
0
0
Hot cathode error
1
0
0
1
Pirani error
The software version of the gauge can be calculated from the value of byte 6 of the
transmitted string according to the following rule:
Version No. = Value
Byte 6
/ 20
(Example: According to the above formula, Value
Byte 6
of 32 means software ver-
sion 1.6)
The pressure can be calculated from bytes 4 and 5 of the transmitted string. De-
pending on the measuring range (hot cathode or Pirani) and the currently selected
pressure unit (
→ byte 2, bits 4 and 5), the appropriate rule must be applied.
As result, the pressure value results in the usual decimal format.
Measuring range hot cathode
(Range of values for byte 4 and 5 = 16666
dec
… 48666
dec
)
p
=
10
(high Byte × 256 + low Byte) / 5333.3) - k1
Where
Pressure unit
k1
mbar
9.125
Torr
9.249903
Pa
7.125
Measuring range Pirani
(Range of values for byte 4 and 5 = 54000
dec
… 60666
dec
)
p
=
10
(high Byte × 256 + low Byte) / 1333.3) - k2
Where
Pressure unit
k2
mbar
42.5
Torr
42.624903
Pa
40.5
Status byte
Error byte
Software version
Calculation of the
pressure value