INFICON BCG450 ATM to Ultra-High Vacuum Triple Gauge User Manual
Page 35
tina40e1-b (2011-04)
35
Bit 1
Bit 0
Definition
0 0
emission
off
0 1
emission 25
μA
1
0
emission 5 mA
1 1
degas
Bit 2
Definition
x
reserved for future use
x
reserved for future use
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
reserved for future use
Bit No. Definition
Message on display
(only BCG450 353-552
and 353-553)
0
diaphragm sensor error
"FAIL Cap"
1
reserved for future use
—
2
Pirani sensor error
"FAIL Pir"
3
reserved for future use
—
4
BA sensor error
"FAIL Ion"
5
reserved for future use
—
6
hardware failure, EEPROM failure
"FAIL EL"
7
reserved for future use
—
The software version of the gauge can be calculated from the response 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