Vaisala HMP230 User Manual download pdf (Page 121)

HMP230 SERIES

M210225en-A Appendix 3: RS 485/422 serial port module

115

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. 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

HMP230 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 re-

turn

yes no

HDX/FDX FDX FDX

When terminal is set to general <lf> (line feed) after <cr> (carriage return),

the listings will have two line feeds if also the HMP230 transmitters send line

feed.

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Vaisala HMP230 User Manual Page 121