DPMS XPQ, User Manual

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DPMS XPQ User Manual
overall length of the RS485 cable connecting all devices can not exceed 1200m
(4000ft). The DPMS XPQ is used as a slave device of a master like a PC, PLC,
data collector or RTU.
If the master does not have an RS485 communication port, a converter has
to be used. Normally a RS232/RS485 or USB/RS485 is adopted. The topology
of RS485 net can be line, circle and star.
1. Line
The connection from master to meter is one by one in the RS485 net as in
fig 2.32.
fig 2.31 Line Mode
In fig 2.32 the Rt is an anti-signal reflecting resistor 120-300 ohm/0.25W.
Normally, it is added to the end of the circuit beside the last meter, if the
communication quality is not good.
2. Circle
Meters are connected in a closed circle for the purpose of high reliability.
There is no need for anti-signal reflecting resistors.
Fig 2.32 Line mode
Converter
Acuvim-X Acuvim-X Acuvim -X
Master
PC