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CONNECTIONS
The connections for the 6-pin RS485 terminal provided (#1 on page 7) are as
follows:
There is an internal short between the two A pins and between the two B pins.
The instrument has no internal line termination. To terminate the line, an external
resistor equal to the characteristic line impedance (typically 120Ω) must be added at
both ends of the line.
Up to 32 units can be connected to the same RS485 line, with a total line length of up
to 1.2 Km using 24AWG cable.
To minimize electromagnetic interferences, use shielded or twisted pair cable to connect
the units.
Each unit is identified by its process ID number (setup item “01”).
The controller acts as a “slave” device: it only answers to commands received from a
“master” device (e.g. an industrial PC) connected to the line.
As additional feature, the controller is also provided with two
pins (5V and 0V) in order to apply the Fail Safe Open Line
protection method. To avoid erroneous readings in Open-
Line conditions, pull-up and pull-down resistors should be
connected as shown.
