CTI 2500-C100, Инструкция по установке и эксплуатации

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CTI 2500 Installation and Operation Guide V2.8 33
Data Manipulation
These instructions provide the ability to search tables, pack and unpack data, and to perform
various shift register operations.
3.4 Analog Loops
The analog loop function supports both velocity and position PID (proportional, integral,
derivative) algorithms. Analog loops are used to control analog processes by varying the loop
output so that the output of the process (Process Variable) matches a target value (Setpoint).
The operation of a particular loop is established by parameters entered by the user. In addition
to executing the control loop, the loop task also provides the same alarm monitoring capability
as the Analog Alarm task described in the next section.
The Setpoint can also be automatically varied using a Ramp/Soak Table. The Ramp/Soak Table
allows you to program a change in the setpoint over time (Ramp) and followed by a period that
the setpoint will remain the same (Soak). Using a series of ramp/soak steps, you can control
most batch processes.
Loops are typically executed on a cyclic basis, independent of the user RLL or SF program
logic. Some models of the CTI 2500 also support the capability of calling a PID loop from the
RLL.
Loops may be cascaded, where the output of one loop becomes the input for the next loop. A
loop may call a Special Function program to perform additional calculations. The number of
loops supported is model dependent. See Section 1.20.
3.5 Analog Alarms
Analog Alarms are parameter-driven functions that allow you to monitor the Process Variable
(PV). Each alarm block allows you to configure up to four absolute-value alarms and two sets of
alarms that monitor the deviation of PV from the Setpoint. In addition, you can monitor the rate-
of change of the Process Variable and detect a broken transmitter. An analog alarm may call a
special function program to perform additional calculations. The number of analog alarm
functions supported is model dependent. See Section 1.20.