User Guide

50
and the external alarm circuit.
Note In order to have the Fail Safe feature activated, an external
power supply has to be connected to the alarm device.
CONTROL THROUGH ANALOG OUTPUT
Instead of configuring relays, it is possible
to have an output signal (selectable
among 0-20 mA and 4-20 mA) propor-
tional to the PID action at the analog output terminals.
With this output, the actual output level amplitude is varied
continuously (with an update delay of 5 seconds) between
the maximum and the minimum values rather than varying
the proportion of ON and OFF times (duty cycle control).
The output signal range can be selected through setup items
O.11 (output #1) and O.21 (output #2).
A device with analog input (e.g. a pump with a 0-20 mA
input) can be connected to these terminals.
The analog output #1 is associated to setpoint 1 and the
analog output #2 to setpoint 2.
To have a control through analog output, a setpoint has to
be configured to “PidL” or “PidH” and the corresponding
output has to be set to Control instead of Recorder: “SEt”
value in setup item O.10 (analog output #1) or O.20 (ana-
log output #2).
In this case no relay can be associated with the same setpoint
to be used for the control, otherwise it is not possible to set
O.10 (or O.20) to “SEt”. On the other hand if a control
through analog output is already associated with a setpoint,
it is not possible to configure a relay to the same setpoint.