Trane Tracer MP580 Programming Manual page 109

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7. If you want a change in the new PID output to be added to the Feed-
back Input for each PID cycle when the program runs, click to select
the Allow Feedback Input check box. A Feedback Input port is added
to the PID block.
NewOutput = Δoutput + FeedbackInput
If this check box is not selected, the previous PID block output is
added to the change in the new PID output for each PID cycle.
NewOutput = Δoutput + OldOutput
Note:
This feature applies to only Tracer MP580/581 Firmware Revi-
sion 2 or higher. Follow the procedure for "Viewing Comm5
parameters" on page 13 to view your current revision number.
8. Click to select the Proportional Only check box if you do not want to
use the integral and derivative contributions of the PID loop.
This is typically used with pneumatic controls or in staging
applications.
9. Type the Proportional Bias if the PID loop is proportional only.
10. Under PID Frequency, enter the time interval at which you want the
PID loop to run.
The PID Frequency defaults to the same frequency as the program.
You may run a PID loop at the same rate as its parent program or at a
slower rate. The time interval must be an integer multiple of the pro-
gram run frequency.
11. Under Output, type the maximum and minimum output percent val-
ues for the loop.
12. In the Disable Position field, type the disable position value.
When the Output Enable/Disable port of the PID block receives a
value of false, the PID loop outputs the disable-position value. Other-
wise, the PID loop outputs its calculated value.
13. In the Fail Safe Position field, type the fail safe value.
When the Fail port of the PID block receives a value of true, the PID
loop outputs the fail-safe-position value. Otherwise, the PID loop out-
puts its calculated value.
14. Click OK.
Using the PID block
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