Chapter 4 _______________________________________________________________ Installation
VAISALA _______________________________________________________________________ 45
Initial Settings
PWD22/52 typically interfaces with a host computer or data logger in an
automatic weather observing system. After the physical connection has
been made, the details of the communication can be configured in the
software. Suitable communication settings depend on the system
implementation.
By default the sensor is on a polled mode. That is, a data message is only
sent when the host computer requests one with a command.
The sensor can also be used in an automatic message mode. The
automatic message mode transmits a new ASCII data message through
the serial line automatically. The interval and message type can be
changed by the user (the AMES command). In addition, the baud rate of
the serial line can be changed to other value, and the data frame can be
selected between 7 data bits, even parity, one stop bit, and 8 data bits, no
parity, one stop bit.
Table 9 describes the default communication settings.
Table 9 Default Communication Settings
Polled or automatic mode, message type
In multipoint communication, where several sensors share the same
communication line, use PWD22/52 in polled mode with distinct
identifiers for individual sensors.
Table 10 lists the commands for changing the default settings. For details
on the commands, see Chapter 5, Operation on page 49.
Table 10 Default Settings Commands
Polled or automatic mode, message type setting
Weather Parameters
PWD22/52 has several changeable parameters, which control the
operation of the present weather algorithm and precipitation
measurement. The parameter values set at the factory have been tested
and found appropriate. They usually do not need to be changed. There
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