SNAP PID MODULE REFERENCE
20
SNAP PID Module User’s Guide
PID Variables
PID variables are used to hold the parameters that you enter using ioManager software, and also
to hold values calculated by the PID module. Unless otherwise indicated, all variables are
entered in raw counts.
Variables Requiring Calculation
If you use ioManager software to enter PID values and other settings for the SNAP-PID-V, you
must calculate in advance the variables listed in the following table. When using OptoENET PID
Module Tuner software, these calculations are done automatically.
Variable
Description
Default
To Modify,
Use Mode...
Scantime Base
(also called
Scantime
Resolution
)
This variable is used to calculate the PID loop basetime
using the following formula:
Basetime (sec.) = .01 x (1 + Scantime Base)
Enter the basetime value you want to use for your PID
loop in the formula and then solve for Scantime Base
using the following equation:
Scantime Base = (Basetime / .01) – 1
Enter the result in the Scantime Base field in
ioManager’s PID Module window.
Range:
0–255 (10 ms to 2.6 sec.)
100 ms
Manual
Scantime Mult
(also called
Scantime
Multiplier
)
This variable is used to calculate the PID loop scantime
using the following formula:
Scantime (sec.) = Basetime x (Scantime Mult + 1)
Enter the scantime value you want to use for your PID
loop in the formula and then solve for Scantime Mult
using the following equation:
Scantime Mult = (Scantime / Basetime) – 1
Enter the result in the Scantime Mult field in
ioManager’s PID Module window.
Range:
0–65535 (10 ms to 1.8 hr.)
10 sec.
Manual
TPO Period Mult
(also called
TPO
Period Multiplier
)
This variable sets the period of the PID module’s TPO
output using the following formula:
TPO Period = (1 + TPO Period Mult) x 256
Enter the TPO period value you want to use for your
PID loop in the formula and then solve for TPO Period
Mult using the following equation:
TPO Period Mult = (TPO Period / 256) – 1
Enter the result in the TPO Period Mult field in
ioManager’s PID Module window.
Range:
0–255 (2.56 sec. to 10.92 min.)
2.56 sec.
Manual
