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Dissolved Oxygen Controller Operation
Teledyne Analytical Instruments 43
On two channel units the next and last display is for trimming the
channel 2 analog input.
3.3.9 PID Assignments
Two independent Proportional Integral Derivative (PID) controllers
are available as options on all instruments, including one channel units.
The sub-menu for assigning the controller inputs is:
Where . . . . represents one of the items from the 4-20 mA
assignment list in Section 3.3.2. The PID controller outputs in turn
represent separate signal sources, and various outputs can be assigned to
them.
Not all signal sources are suitable as inputs to a PID processor, and
an asterisk on the display marks the selections that are unavailable.
Potentially useful sources, such as the process value, temperature, and
quantities derived from the measured process value(s) are normally
available. The assignment should be set to “unused” if no controller is
needed. This will prevent the PID setup displays from appearing in the
operational section.
Either PID processor can be assigned to a signal from either
channel, and they can both be assigned to signals on the same channel,
but they cannot be assigned to the same signal on the same channel. The
current selection will be preceded by a question mark on the display if
making it permanent would result in duplication.
Up to two 4-20 mA outputs and up to two relays can be assigned to
each PID processor output. The output of the PID processor is discarded
if nothing is assigned to it.
If a 4-20 mA output is assigned to a PID processor there will be no
display for it in the setup section of the operational displays, as the 4-20
output scaling is fully specified by the PID setup parameters in the same
section. If relays are assigned to a PID output there will be setpoint
PID A: …..
PID B: …..