Vaisala HMP230 - Manual (Page 36)

HMP230 SERIES
User's Guide
M210225en-B
30
When the jumper is inserted the serial line factory settings become valid, but
only temporarily. The transmitter must be given new settings; otherwise
the transmitter uses the old, unknown settings after power-up. When the
new settings have been given, the transmitter must be reset. The jumper must
be removed before the transmitter is reset; if the jumper is in place when
power is turned on, the transmitter does not work.
After jumper insertion the transmitter is in STOP mode, ready to receive
commands.
The same method is used when the transmitter is in POLL mode and the user
has forgotten its address.
CAUTION
Inserting a jumper in any other place in connector X16
voids the guarantee of the transmitter.