INFICON VGC403 Three-Channel Measurement and Control Unit - Manual (Page 27)

tinb07e1-e 2011-07 Vacuum Gauge Controller
27
5.3 General parameters (PArA
GEn
)
These parameters are used for general configuration of
the unit. The parameters affect all channels.
5.3.1 Unit of measurement (unit)
Unit of measurement for pressure values. The unit affects
displayed pressure readings, threshold values, etc.
Tab. 5-8 unit parameter values
The unit of measurement is indicated on the display. See
Fig. 4-1,  15, Pos. C. For information on common pres-
sure units refer to Section «Conversion tables»,  50.
NOTE:
The pressure unit «Torr» can be locked. In this case
torr
is not available for selection. See Chapter 5.4.4
Torr lock (tr-L),  30.
5.3.2 Baud rate (bAud)
Transfer rate of the RS232C interface.
Tab. 5-9 bAud parameter values
5.3.3 Display format (diGit)
Number of digits shown in the display.
Tab. 5-10 diGit parameter values
NOTE:
The diGit parameter has no effect on CDG sensors.
NOTE:
When PrE is enabled, the display of PSG and PCG
gauges in the pressure range p < 10
-4 mbar is re-
duced by one digit.
5.3.4 Default parameters (dEF)
Reset all parameters to the default values (factory set-
tings). Please note that this action cannot be undone.
Proceed as follows to reset the parameters:
1 Select the dEF parameter
2 Press both the UP and the DOWN button at the
same time
• The display shows SEt
• All parameters are reset to the default values
5.3.5 Recorder output (Ao)
The recorder output is a programmable analog output.
The recorder output voltage is a function of the pressure
on the sensor. The relation between the pressure and the
voltage is called the characteristic curve of the output. It
can be selected.
Modifying parameter
1 Select the Ao parameter
2 Use the CH button to assign the recorder output to
a channel
3 Use the arrow buttons to select the characteristic
curve of the output
• The value of the parameter is changed
Characteristic curves
Fundamentally we have to distinguish between logarith-
mic and linear characteristic curves. A logarithmic char-
acteristic curve is useful if the pressure range covers sev-
eral orders of magnitude in the measurement. In this case
it is appropriate to take the logarithm of the pressure and
then scale the result in a suitable manner.
A linear characteristic curve is useful if the pressure
range covers only a few orders of magnitude in the mea-
surement. In this case the recorder output voltage is pro-
portional to the pressure value. You can specify which
pressure value will result in the maximum output voltage.
The available characteristic curves will be described in
the following. In each case it is shown how to calculate
the pressure p (in mbar) from the recorder output voltage
U (in volts).
Display Significance
bAr Pressure unit mbar or bar
torr Pressure unit Torr
PASC Pressure unit Pascal
uC Pressure unit Micron
Display Significance
9600 9600 Baud
19200 19200 Baud
38400 38400 Baud
Display Significance
2 Two digits
e.g. 2.5 -1 or 370
3 Three digits
e.g. 2.47 -1 or 373