Vaisala HMT130 - Manual (Page 55)

Chapter 4 ________________________________________________________ Serial Line Operation
VAISALA ________________________________________________________________________ 53
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]<cr>
where
aa = address of the transmitter (0 ... 99)
CLOSE
The CLOSE command switches the transmitter back to the POLL mode.
CLOSE<cr>
Example:
>OPEN 2 (opens the line to transmitter 2, other
transmitters stay in POLL mode)
>CRH (for example, calibration performed)
...
>CLOSE
(line closed)