Vaisala PTU300 - Manual (Page 101)

Chapter 4 _________________________________________________________________ Operation
VAISALA ________________________________________________________________________ 99
Communicating with a Transmitter in POLL
Mode
OPEN
When all transmitters on the RS-485 bus are in POLL mode the OPEN
command sets one transmitter temporarily to STOP mode so that other
commands can be entered.
OPEN [aa]
where
aa = Address of the transmitter (0 ... 255)
CLOSE
The CLOSE command switches the transmitter back to the POLL mode.
Example:
>open 2 (opens the line to transmitter 2, other
transmitters stay in POLL mode)
>crh (for example, calibration performed)
...
>close
(line closed)