Smartune Automatic Loop Tuning - Siemens SIMATIC 505 User Manual

SmarTune Automatic Loop Tuning

162 • • • • 9 - PID Loops
Table 9.2
BIT
1 1= Restart at the first step. To restart, toggle bit off, on, then off again. The restart
occurs on the trailing edge of a square wave.
2 1= Hold at current step. To hold, set bit on.
3 1= Jog to next step. To jog, set bit on. Jog occurs on the rising edge of a square
wave.
4 1= Finish. Indicates ramp/soak is completed.
5 1= Wait. This bit is set during a soak period when the process variable is not within a
specified deviation from the SP. The loop holds the soak timer when bit 5 is set.
6 1= Hold in progress at current step.
7-8 Unused ( always returns 0 ).
9-16 1= Contains step number loop is currently executing. Step number is zero-based.
Step number contains 0 when ramp/soak is on step #1, 1 when the ramp/soak is on
step #2 etc.
1. Enter an address: C,Y,V, or WY in the RAMP/SOAK FLAG
ADDRESS field. If you select NONE, no data is written from
the Loop Ramp/Soak Flags. See the following table for Loop
Functions Bits.
2. To edit the selected Ramp/Soak step number, click on the dialog
box EDIT button or use the keyboard to Tab to the EDIT button
and press Enter or (Alt + E). The following dialog box appears
(Figure 9.5).
Figure 9.5
3. Select Ramp, Soak, or End from the Mode field:
•
The RAMP step changes the loop setpoint (you can enter
the setpoint in the Setpoint field) linearly from its current
value to a new value at a specified rate of change (you can
enter the rate of change in the Ramp Rate field). You can
program a status bit (C or Y) for each step of the ramp/soak.
This bit is set to 1 when the loop is executing this step. It is
reset when the loop leaves the step.
•
The SOAK step holds the setpoint constant for a specified
period of time (you can enter a soak time in the Soak Time
field). You can guarantee a soak period by entering a
deadband value (you can enter a deadband in the Deadband
field). This form of soaking ensures that the PV is within a
specified deadband around the setpoint for a specified
period of time.
•
The END step terminates a ramp/soak profile. When the
program reaches an end step, the loop remains in automatic
mode and holds the setpoint constant.
SmarTune is an automatic PID loop tuning process that is built into the
new SIMATIC 555 CPUs with Release 5.0 or greater firmware.
LOOP/FUNCTION
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