User's Manual
9
Note: The RAD-ISM-900-UD Receiver Analog Output is a 3-wire device and should be
wired to the RTU/PLC just as you would a normal 3-wire current loop device. This wiring
confi guration is for the Receiver only and must be followed regardless of the type of
current loop device on the Transmitter side of the loop (i.e., 2-wire, 3-wire, or 4-wire).
Example A
RF Link contact is wired to a warning light using the (NC) contact. As soon as the
RF Link has been established, this contact will go to Open and the warning light will
go out.
The 4-20mA Analog output has been wired directly to a meter or RTU/PLC device
and will MAINTAIN LAST STATE if the RF Link is lost.
Discrete Output 1 has been wired through the (NO) contact. When voltage is
applied to the Discrete Input 1 side of the Transmitter, this contact will go Closed,
and the pump will start.
Example B
RF Link contact is wired to a warning light using the (NC) contact. As soon as the
RF Link has been established, this contact will go to Open and the warning light will
go out.
The 4-20mA Analog output has been wired directly to a meter or RTU/PLC device
and will MAINTAIN LAST STATE if the RF Link is lost.
An interesting feature in this example is wiring of the pump. Discrete Output 1 has
been wired through the (NO) contact, and through the RF Link (NO) contact. This
immediately shuts off the pump if the RF Link is lost. By wiring through the RF Link
contact this way, the RF Link contact will go Open when the RF Link is lost, and
the pump will shut down. This overrides the default for Discrete Output 1, which
MAINTAINS LAST STATE.
Default OFF Wiring
If either one or both of the Discrete Outputs and/or the Analog (4-20mA) are
required to default OFF upon loss of the RF Link with the Transmitter, the RF Link
Output can be used to provide a Default OFF state.
Discrete Wiring
By wiring the Discrete Output(s) in series through the (NO) contact of the RF
Link, the LAST STATE of the Discrete Output(s) will be overridden and forced to
go Open.
Note: Current rating of RF Link contact is 0.5A max.