Vaisala PTB200 - Manual (Page 24)

PTB 200 23 (28)
Digital Barometers
SSD/Operating Manual 24th February 1993 PTB200-O0284-1.1
The following pressure adjustments are possible:
• offset adjustment
• offset/gain adjustment
• multipoint adjustment at up to eight pressure levels.
Offset and offset/gain adjustments are made with the barometer
connected to a reference pressure (see LP command). With the LP
command the pressure value of the primary standard is given to the ba-
rometer as a reference pressure and no separate corrections are
needed.
Before multipoint adjustment, the barometer must first be precalibrated
in order to find out the corrections needed to bring the barometer to the
accuracy level of the primary standard. After precalibration the
multipoint corrections are entered through the serial interface (see MPC
and MPCI commands).
Note that up to 99 PTB 200 barometers can be connected to one RS
232C bus which makes their adjustment and calibration more cost
effective.
4.1 Offset and gain adjustment
LP Linear pressure adjustments
LP
The LP command is used in offset and offset/gain adjustment of the
barometer.
The offset adjustment can be made at any pressure level. To guarantee
the best possible pressure stability connect the pressure port of the
barometer to the pressure standard even during offset adjustment. The
two pressure levels used in offset/gain adjustment must be at least 400
hPa apart.
Change the MEMORY jumper to the EEPROM write enable position.
Example of an offset adjustment:
>LP
Ref1 ? (set pressure level and enter value
here)
P : (the current non-corrected value
appears here)
Ref2 ?