Vaisala HMP228 - Manual (Page 23)

HMP228
M210282en-A Operating Manual
17
NOTE
When the serial bus settings are changed, the transmit-
ter has to be reset before the new settings become ef-
fective.
The processor does not allow the following combinations:
• no parity, 7 data bits, 1 stop bit: if this combination is given the
HMP228 programme will change the number of stop bits to 2
• even or odd parity, 8 data bits, 2 stop bits: if this combination is given
the programme changes the number of stop bits to 1
Refer to the manuals of the PC and the terminal emulation programme when
giving serial settings.
The RS 232C screw terminal cannot be used if an RS 485/422 serial module
or a current loop module is used. See Appendices 3 and 4 on how to install
and operate these modules.
In calibrating or changing the settings of the transmitter it can be more con-
venient to use the connector X17, if connector X6 is already in use. This con-
nector, however, transfers only RS 232C signals. If an RS 485/422 serial port
module or a current loop module has been installed, it has to be removed be-
fore communicating through the X17 connector.
NOTE
Some PC computers can generate interferences to the
measured humidity and temperature values if the
transmitter and the PC are connected to different mains
outlets. To minimize the possibility of these interfer-
ences, always use the same main outlet (same phase of
the main electricity) for the PC and the power supply of
HMP228. It is always preferable to use the connector
X16 instead of the connector X17 because it is more
immune to interferences.
The serial commands are described in Appendix 1.