Maintenance and service
GA 09.035/6.02 - 07/2011 - © Oerlikon Leybold Vacuum
87
7.3
Calibration
7.3.1
Basics
The Multi-Channel Controller can only measure with high accuracy when it is
calibrated precisely. The Multi-Channel Controller is calibrated by Oerlikon
Leybold Vacuum before it is shipped. Normally there is no need to change the
calibration data.
Calibration.
If you input incorrect calibration data, the Multi-Channel Controller cannot
perform accurate measurements anymore.
The interface commands for calibrating the unit are intended for service
technicians of Oerlikon Leybold Vacuum only.
The calibration affects the A/D converters of the individual channels. The mea-
suring curve of an ideal A/D converter is a straight line which has a slope of
one and runs through the origin, i.e.:
Factor = 1 (slope of the line)
Offset = 0 (intersection with the y axis)
The curves of real A/D converters differ slightly from these ideal values. Cali-
brating the unit means to determine the gain factors and the offset voltages of
the individual A/D converters and to store these calibration values.
The interface commands CAF and CAO are used to access the calibration
data of the unit.
7.3.2
CAO
Calibration offset. Calibration offset of the A/D converter. The command is
intended for service technicians of Oerlikon Leybold Vacuum only.
S: CAO[,±a.aaaaE±aa,±b.bbbbE±bb,±c.ccccE±cc] <CR>[<LF>]
R: <ACK><CR><LF>
S: <ENQ>
R: ±a.aaaaE±aa,±b.bbbbE±bb,±c.ccccE±cc<CR><LF>
Note:
The CAO command can also be used with other parameters. See
Chapter 7.3.4 Calibrating the unit,
88.
Caution
Parameters
Significance
±a.aaaaE±aa
Calibration offset of channel 1
±b.bbbbE±bb
Calibration offset of channel 2
±c.ccccE±cc
Calibration offset of channel 3
