Vaisala PTB220 User Manual
Page 95
A
PPENDIX
E ___________________________________________________________ A
NALOG OUTPUT
V
AISALA
_________________________________________________________________________ 89
1. Open the cover of the barometer and set the dip switch SW4 to
upward position (ON).
2. Use the serial line to give the command LC OFF, which deactivate
the linear correction.
3. Give the command ITEST X
1
and measure the output current /
voltage. X
1
is a value close to the lower end of full range, for
example, 0.5 in voltage or 5 in current output mode.
4. Give the command ITEST X
2
and measure the output
current/voltage. X
2
is a value close to the upper end of full range,
for example, 4.5 in voltage or 19 in current output mode.
5. Calculate the gain and offset corrections using following
equations. The parameters are in milliamperes or volts.
1
2
1
2
MeasX
MeasX
ItestX
ItesX
Gain
−
−
=
(E-1)
1
1
MeasX
Gain
ItestX
Offset
⋅
−
=
(E-2)
6. The corrections are given with the command DLCI. Please note that
the programme requests the corrections for both analog modes.
Give the calculated factors only and acknowledge the values with
enter (
enter (
Example of calculating and giving the linear an offset/gain
corrections:
ItestX
1
= 0.5 V
MeasX
1
= 0.502 V
ItestX
2
= 4.5 V
MeasX
2
= 4.506 V
Offset = -0.001499
Gain = 0.999001
>dlci
U offset
: ?
-0.001499
U gain
: ?
0.999001
I offset
: ?
I gain
: ?
CORRECTIONS SAVED
>
7. Activate the linear correction with the command LC ON and reset
the barometer.
8. The correction can be checked with command ITEST x, where x is
0...5V or 4...20mA.