USER'S GUIDE ____________________________________________________________________
40 __________________________________________________________________ M210543EN-F
Communication Options
PWD22/52 has one serial line with two interfaces. The two-wire RS-485
is the standard interface. The PWD22/52 software is designed to allow
the RS-232 interface to be used as a service line, when the RS-485
interface is connected to the host computer.
Usually, PWD22/52 waits for input from both the RS-232 and RS-485
interfaces. Any character from the RS-232 interface disables the RS-485
communication for 10 seconds or until the line is closed by the operator.
Automatic messages are sent to both interfaces along with the messages
polled from the RS-485 interface.
Serial Communication Settings
The default settings of the serial communications port are:
- 9600 baud
- Even parity
- 7 data bits
- 1 stop bit
Serial Transmission RS-232
For the RS-232 communication, connect the PWD22/52 signal wires:
- YEL to PC 3/9: TxD RS-232
- GRN to PC 2/9: RxD RS-232
- GRY to PC 5/9: GND
Vaisala recommends that the maximum length of the RS-232 cable is
50 m. Usually, the RS-232 connection can be used with distances up to
100 m without problems but that cannot be guaranteed.
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