User`s guide

Chapter 2 __________________________________________________________ Product Overview
VAISALA_______________________________________________________________________ 35
DSI486 is a dual-isolated communication module, which can be used in
the RS-232, RS-485, or SDI-12 mode. The communication mode is
selected by the correct wiring of the I/O pins and with the correct
jumper settings on the board. The DSI486 module is used, for example,
for connecting displays, terminals, and the data logger together when
the distance is longer than 15 meters. The maximum distance for
DSI486 is approximately 1500 meters at full speed. The DSI486
module must be configured before using it in order to work as desired.
The RS-485/422 channels A and B are galvanically isolated from the
host board's electronics. The +5 VDC power supplies of channels A and
B are also isolated from each other with capacitors. Thus, it is possible
to wire these two channels to separate locations.
The RS-232 mode utilizes channel B. When channel B is used in the
RS-232 mode, it is possible to use channel A as a galvanically isolated
two-wire RS-485 channel. The RS-232 channel is galvanically
connected to the host board's GND potential.
The SDI-12 channel has its own connecting point on the board. It does
not use channel A or B for the communication. SDI-12 is galvanically
connected to the host board's GND potential.
Modem Module
The DMX501 modem module is used for providing long distance fixed
line connection between two Vaisala devices with a similar interface. It
is used when the distance is up to 10 km, for example, between MAWS
and Digital Display, or between Ceilometer CT25K and MAWS.
Through this I/O port, a remote location can send reports and data or the
host can poll them. The DMX501 modem module must be configured
before using it so that it works as desired.