Terminals I+ and I- are supplied as a blue terminal strip on
units supplied as Ex versions. This means that a sensor fitted in
the hazardous area can be directly connected to the unit.
3.5 Connecting further peripheral instrumentation (output)
If there is a possibility of electrical transients on long signal
cable runs we would recommend that an overvoltage protection
unit is used. A current signal is available at the passive output
of the unit, terminals O+, O- and O+H, which can be used for
connection to further instrumentation such as displays, printers,
recorders or PLC systems. The front mounted yellow LED
illuminates when current flows in the output circuit.
Please take note of the respective volt drop when including the
communication resistance in the current circuit!
The HART
®
-programming up module for sensor setting up can,
in this case, be directly connected to the two front mounted
communication sockets without any further wiring.
2-wire current connection without
HART
®
-communication resistance
2-wire current connection with HART
®
-communication resistance
Active barrier
20
Summary of Contents for RN 221N
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