D8 Series User’s Guide
Chapter 4: Operation and Setup
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• A process alarm occurs and is unacknowledged. The global alarm occurs only if the alarm
function is set to
standard
in the
Alarms
menu. (The global alarm does not occur if the alarm
function is set to
boost
.)
The global alarm output stays active until all alarms have been acknowledged.
When the global alarm output is active, it conducts current to the controller’s dc common. When the
global alarm output is not active, it does not conduct current.
NOTE!
You cannot configure any parameters for the global alarm. The active state of the
global alarm output is NOT affected by the D/O alarm polarity parameter in the Global
setup menu.
Setting Up Process Variable Retransmit
The process variable retransmit feature retransmits the process variable of one loop (primary) via the
control output of another loop (secondary). This signal is linear and proportional to the engineering
units of the primary loop input.
Typical uses include data logging to analog recording systems, and long distance transmission of the
primary signal to avoid signal degradation. The retransmitted signal can also be used as an input to
other types of control systems such as a PLC.
Any available heat or cool output may be used as a retransmit output. Any process variable may be
retransmitted, including the input from the same loop.
To get a 4 to 20mA or 0 to 5VDC signal, the controller output signal must be connected to a
Serial DAC.
How to Set Up Process Variable Retransmit
1. Configure all of the setup parameters for the primary loop (the loop whose input signal will
be retransmitted).
2. Choose an unused control output to retransmit the input signal. This output may be on the
primary loop or on a different loop.
3. On the secondary loop (the loop whose output will retransmit the signal):
– Set up the parameters in the
PV retrans
menu. Process Variable Retransmit Menu on
– Enable the loop’s output and configure it to meet the requirements of the application.
4. If the signal is being retransmitted to another controller, configure the input of that controller
to accept the linear output signal produced by the retransmit output.
Process Variable Retransmit Example: Data Logging
The D8 controls the temperature of a furnace. The thermocouple in one of the zones is connected
to the controller and is used for closed-loop PID control. An analog recorder data logging system is
also in place, and a recording of the process temperature is required. The recorder requires a linear
4 to 20mA input signal, which represents a process variable range of 0 to 1000°F.
