Chapter 4_________________________________________________________________ Installation
VAISALA ________________________________________________________________________ 41
Initial Settings
Vaisala Present Weather Detector PWD22 is typically interfaced to a
host computer or a 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 implementation of the whole
system.
By default the sensor is on a polled mode, in other words, a data
message is only sent when the host computer requests one with a
special 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.
The default communication settings are described in Table 8 below.
Table 8
Default Communication Settings
Setting
Default
Baud rate
9600 bps (7E1)
Polled or automatic mode, message type
Polled mode
Sensor ID
No ID set
In multipoint communication, where several sensors share the same
communication line, PWD22 should be used in the polled mode and
individual sensors must have distinct identifiers.
The commands for changing the default settings are listed in Table 9
below. For details on the commands, refer to Chapter 5, Operation on
page 55.
Table 9
Commands for Changing Default Settings
Operation
Command
Baud rate selection
BAUD
Polled or automatic mode, message type
setting
AMES
Sensor ID configuration
CONF
