Vaisala MMT330 - Manual (Page 96)

User's Guide _______________________________________________________________________
96 ___________________________________________________________________ M210764EN-F
Outputting Reading Once From All Transmitters
Use the DSEND command to output the reading once from all connected
transmitters that are in STOP or POLL modes. In order to avoid data
collisions, the transmitters will send their response after a suitable delay.
The response includes the transmitters’s address, followed by their
measurement message.
NOTE The total execution time of the DSEND command depends on the bit rate
of the serial port connection. At slow speeds, it will take a considerable
amount of time for devices with large address number to respond. The
delay will be the same even if there are no other devices at all.
DSEND
Example (transmitters with addresses 3 and 25 responding):
>dsend
3 aw= 0.261 T= 23.8 'C
25 aw= 0.277 T= 23.5 'C
>
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 ... 99)
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)
>? (for example, display device information)
...
>close
(line closed)