Vaisala HMP260 User Manual
Page 99
HMP260 SERIES
Appendix 3: RS 485/422 serial port module
HMP260-U017en-1.5
POLL mode
If a transmitter has been set to POLL mode, it will respond only to commands
sent with its address:
send 22
RH= 24.4 %RH T= 29.1 'C
Addresses from 1 to 99 can be used. According to the RS 485/422 standard a
maximum of 32 devices can be connected on same bus, but the number can be
increased if the line length and/or baud rate is reduced.
More than one baud rate can be used on an RS 485 line. E.g. the host of the
line can use different baud rates with different devices (this makes it possible
to use the same address for several devices).
The line terminations must be dynamic; e.g. RC circuit is used instead of a
simple resistor termination. Each RS 485 module has a dynamic line
termination so it can be used at the end of a line.
RS 485 network settings
HMP260 settings
single pair
dual pair
Full duplex/half duplex
HDX
FDX
Echo on/off
OFF
ON
Terminal settings
Line feed after carriage
return
yes
no
HDX/FDX
FDX
FDX
When terminal is set to general
the listings will have two line feeds where also the HMP260 transmitters send
line feed.