Watlow Electric Ramping and Profiling Microprocessor-Based Control SERIES 1500 - Manual (Page 23)

C.
D.
E.
F.
While in the HALT condition, the Series 1500 maintains the Set Points and
Event Output conditions from the step it was in when it was halted, or from last
step before a “Blank Step” halted the control. If you restart the control, having
made no change to the step data, the 1500 will complete the step from the time it
stopped. If you change data, the step begins from beginning.
Thus, if your sample program did not have “Recycle” activated, it would halt
after performing Step #8, but would continue to hold the oven at 110°,
65%RH, and with Ch-1 Events 3 and 4 ON and Ch-2 Events 1 and 3 ON.
If you press the RUN/HALT key at 1-1/2 minutes into Step #5, it would Halt
with the oven at 275°, 83.2%RH, and have Ch-1 Event 1 ON and Ch-2
Event 2 ON.
However, you may not want the Step #8 conditions to be retained until
tomorrow. You could add a step at the end of the program to establish
Set Points of 75°, 50%RH, and with all Event OFF.
2. Ramping Conditions
A. When running any Set Point step, the Series 1500 notes what the
existing starting conditions are and what the desired ending conditions are.
Then it follows a linear path between the two.
B. Although the desired ending conditions are specifically programmed into
each step, the beginning conditions depend on the step performed just
previously. Know where you are going and where you've been.
C. Step #4 of your Sample Program is an example:
l
As the chart on page 17 shows, you expect to start Step #4 at 400°, and
ramp uniformly down to 275°. This certainly is what happens on the first
time through Step #4.
l
But when you “loop back-from Step #6, your starting point is 11 O°. You
will be ramping upward from 11 O° to 275°.
l
If this is not acceptable to you, you might want to jump loop back to Step
#2 to reach a full 400° through Step #3 before you start Step #4.
3. Wait Step
A. A Wait Step maintains the same Set Points that existed at the end of the
previous step. With Step #1 as a Wait Step, this means that the 1500 will
use the default values for Step #1 (75°, 50%RH, ail events OFF) during its
first run. However, when it recycles from Step #6, it will retain the Step #8
values (11 O°, 65%RH, Ch. #1 Events 3 & 4 ON and Ch. #2 Events 1 & 3
ON).
If you were to halt the program during Step #3 and then “RESTART’ and run
it, Step #1 would retain the Step #3 values. Since this is not always desirable,
you could place a short (1 second) step immediately before the Wait Step to
establish different Set Point values.
B. When waiting for "Time,” program all three units (HR-MN-SC). If you program
“53” for Minutes, but enter nothing for Hours or Seconds, the programmed
time will be 53 minutes after midnight.
Sample Program, Chapter 2 WATLOW Series 1500 Manual
23