11
Operation
6
Operation
6.1 Before switching on
After switching on the power supply, the transmitter is ready for operation. However, it is
advisable to wait for a stabilization period of 5-10 minutes before measurement, and to
operate the transmitter without interruption during the measurement process.
The pressure measured in the Pirani range depends on the gas type. To adjust for differ-
ent gases, a corresponding gas type correction factor can be set on the transmitter; this
generates correct measurements in the pressure range below 1 mbar. The gas type cor-
rection factor is factory-set for air and N
2
to 1.00
(see p. 18, chap. 10.3)
.
6.2 Configuring the data exchange
Communication is carried out, depending on the address selector switch setting, via the
serial RS-232 interface using the relevant display units or via RS-485 using the Pfeiffer
Vacuum protocol:
●
9600 baud
●
8 data bits
●
1 stop bit
●
no parity
Parameter overview
Parameters are displayed in square brackets as a three-digit number in bold font. The
designation may also be stated if necessary.
Example:
[P:312] Software version
Reading the actual
pressure value
[P:740]
Pressure value as the value to be queried and also as equalization (see below) are trans-
mitted by means of a string in the format "
aaaabb
", whereby "
aaaa
" is the mantissa and
"
bb
" the exponent with offset 20 of an exponential number. "
aaaa
" is therefore in the
range "1000" (for 1.000) to "9999" (for 9.999). The individual characters of the string are
the numbers "0" (ASCII 48) to "9" (ASCII 57).
Example
: "104223" represents 1.042 x 10
+3
mbar, "750015" represents 7.500 x 10
-5
mbar.
#
Name
Data type
Handling
CPT 100
PPT 100
RPT 100
HPT 100
MPT 10
0
40
DeGas
6 - boolean_new
readable, writable
•
41
Sensor on/off
7 - u_short_int
readable, writable
•
•
49
Switch mode
7 - u_short_int
readable, writable
•
•
•
303
Actual error code
4 - string
read-only
•
•
•
•
•
312
Software version
4 - string
read-only
•
•
•
•
•
349
Component name
4 - string
read-only
•
•
•
•
•
740
Pressure in [mbar]
10 - u_expo_new
readable, condition-
ally writable
•
•
•
•
•
741
Pressure set point
7 - u_short_int
only writable
•
•
•
•
•
742
Correction value
(Pirani)
2 - u_real
readable, writable
•
•
•
•
743
Correction value
(Bayard-Alpert)
2 - u_real
readable, writable
•
743
Correction value
(CC sensor)
2 - u_real
readable, writable
•
