Vaisala HMP228 User Manual
Page 92
HMP228
Appendix 4: RS 485/422 serial port module
M210282en-A
86
POLL mode
If a transmitter has been set to POLL mode, it will respond only to commands
which include its address:
send 22
aw= 0.244 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.
The line terminations must be dynamic; e.g. an RC circuit is used instead of a
simple resistor termination. Each RS 485 module has a dynamic line termina-
tion so it can be used at the end of a line.
RS 485 network settings
HMP228 settings
single pair
dual pair
Full duplex/half duplex
HDX
FDX
Echo on/off
OFF
ON
Terminal settings
single pair
dual pair
Line feed after carriage return
yes
no
HDX/FDX
FDX
FDX
When terminal is set to general
the listings will have two line feeds when also the HMP228 transmitters send
line feed.