Vaisala PTB210 (serial) - Manual (Page 21)

Chapter 4 ________________________________________________________________ Operating
VAISALA _______________________________________________________________________ 19
.CALD Setting the Calibration Date
With this command, the last calibration date can be stored in the
memory of the barometer.
.CALD.xxx
xxx = calibration date; max. 15 characters
Example:
.CALD.991015
Setting the RS485 Terminating
Resistor On/Off
The PTB210 series barometers have a built-in RS485 terminating
resistor, which is set, as default,
OFF
. The resistor can be set either
ON
or
OFF
with the .
ROFF
/.
ROFF
commands. If the barometer is in the end
of the serial line, the resistor should be set ON , especially, when long
cables are used.
In case several barometers are connected to same line, only the
resistor of the last one is set
ON
, with the others it should be
OFF
. This
prevents formation of excessive load on the line. The maximum
amount of barometers on same line is 32.
At the end of the serial bus there must be a PTB210 barometer, a
dynamic line adapter or a line master (see figure below).
HOST
COMPUTER
PTB210
RX/TX
HI
LO
RX/TX
HI
LO
RX/TX
HI
LO
RX/TX
HI
LO
120R
33nF
DYNAMIC LINE TERMINATION REQUIRED
IF NO DEVICE AT THE END OF THE BUS
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