User Manual

32 tina03e1-b (2004-02) BPG400 v1.om
Bit 1 Bit 0 Definition
0 0 Emission off
01
Emission 25
µA
1 0 Emission 5 mA
1 1 Degas
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 BA 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 currently selected pressure unit (
→ byte 2, bits 4 and 5), the ap-
propriate rule must be applied.
As result, the pressure value results in the usual decimal format.
p
mbar
= 10
((high byte × 256 + low byte) / 4000 - 12.5)
p
Torr
= 10
((high byte × 256 + low byte) / 4000 - 12.625)
p
Pa
= 10
((high byte × 256 + low byte) / 4000 - 10.5)
Status byte
Error byte
Software version
Calculation of the pressure
value