
15 TX+/RX+
16 TX-/RX-
USER RS485
INTERF
ACE
TX+/RX+
TX-/RX-
MCT 1302
24 +mA
23 +Volt
ANALOG
INTERFECE
CURRENT
VOLTAGE
22 GND
GND
MCT 1302
Page 12
RS485
Through serial RS485 interface, it is possible to make serial connections for long distances (up to 1000 m).
The RS485 serial connection is of the 2-wire type, and allows to connect up to 32 instruments to a
single MASTER unit (personal computer, PLC, etc.) using a twisted and shielded cable, taking care to
connect the screen to the ground at only one of the two ends.
The cable must not be channeled with other cables (i.e. outputs connected to contactors or power ca-
bles), but must possibly follow its own path.
The PC used for the connection must comply with the EN 60950 standard.
NOTE: If there is a fieldbus, the RS485 is not available.
ANALOG OUTPUT (OPTIONAL)
The instrument provides an opto-insulated analog output in current and/or voltage.
Features:
• Analog voltage output: range from 0 to 10 Volt or from 0 to 5 Volt, minimum load 10KΩ
• Analog current output: range from 0 to 20 mA or from 4 to 20 mA. The maximum load is 300Ω.
To make the connection, use a shielded cable, taking care to connect the screen to ground at only one
of the two ends.
The analog sending can be sensitive to electromagnetic disturbances, it is therefore recommended that
the cables are as short as possible and that they follow their own path.
Warning: do not connect the analog output to active devices.