Vaisala PTB330 - Manual (Page 53)

Chapter 4 ________________________________________________________________ Operation
VAISALA _______________________________________________________________________ 51
Using Serial Line
Pressure 3h trend and tendency reading is also available through serial
line. Key in the lines below:
>form "trend=" P3H " " "tend" A3H #RN
>
For more information on the Form command, see section Changing
Quantities and Units on page 70.
Missing Trend
When the pressure tendency has not yet been calculated, that is, the
device has been powered-up less than three hours ago, the PTB330
barometer outputs a code "*" when viewing via serial connection. The
absence of the pressure trend is indicated in a similar manner, too.
Graphic History
The graphical display shows the data trend of the selected quantities,
one at a time. The graph is updated automatically while measuring.
Use the following functions in the graphical display:
- Press the NEXT button to have the trend graph and max/min graph
in turns and browse through the quantities selected for display.
- Press the EXIT button to return to the basic display.
Figure 32 Graphical Display
Trend graph: Displays a curve of average values. Each value is a
calculated average over a period.
Max/min graph: Displays the minimum and maximum values in a
form of curve. Each value is max/min over a time period. See Table 8
on page 52.