Watlow Series SD31 PID with Optional Countdown Timer - Manual (Page 38)

Wa t l o w S e r i e s S D 3 1 ■ 36 ■ C h a p t e r 8 Ti m e r
The optional countdown timer (SD31-XXXX-XTXX only) provides a versatile timer function that allows countdown
timing that can toggle set points and trigger outputs based on timer settings. During timing, the controller can au-
tomatically change to a different set point, and then revert to the original set point after timing completes. Either
or both of the SD31's outputs can be designated for the timer output function, which will allow the timer to manip-
ulate the output before, during, and after timing. Timing can also be linked to the ready band, which can stop the
timer sequence if the process temperature deviates from the current controller set point. The timer can be used in
either the automatic mode or the manual mode, with setting support for both open loop and closed loop set point
presets.
Timer Sequence
The timer can always be started by pressing the Down ¯ key from the Home Page. A timer sequence can include:
• Switching to a timer set point.
• Counting down the time.
• Triggering a timer output.
• Stopping the countdown using the ready band.
Countdown Timer Keys
• To start the timer sequence - Press the Down ¯ key
• To re-start the timer sequence at the beginning - Press the Down ¯ key
• To acknowledge the ready state when using the ready with acknowledge method - Press the Down ¯ key
• To stop the timer sequence before it is complete - Press the Up ¿ key
Countdown Timer Displays
Timer Colon - The colon helps to indicate the status of the timer function. The colon blinks when timing is occur-
ring and is lit steady when timing is paused or not occurring.
Time Display - The time for the countdown timing is recorded in terms of hours, minutes, and seconds. The dis-
play of the time is a floating display that will display in hours and minutes until the hours countdown to zero, at
which time the display will shift to displaying minutes and seconds.
Colon Blinks Colon Steady
During timer countdown Before and after timing
After countdown, but during signal timing When waiting on the Ready Band
Countdown Timer
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