Vaisala PTB200 User Manual download pdf (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<cr>

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<cr>

Ref1 ? (set pressure level and enter value

here)<cr>

P : (the current non-corrected value

appears here)

Ref2 ? <cr>

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Vaisala PTB200 User Manual Page 24