Watlow F4P Series, User Manual, Page: 66 / 124

7 . 8
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F e a t u r e s Wa t l o w S e r i e s F 4 P
Multiple PID Sets
The Series F4P supports up to five heat/cool PID sets.
This feature is extremely valuable if the characteristics
of your thermal system vary over its operating range. All
PID sets can be auto tuned or manually tuned. PID sets
can be edited in the Operations Page. The Series F4P can
be programmed to operate using any of the five sets
based on crossover points of the set point or process val-
ue. These programming choices are made in the Opera-
tions Page > PID Crossover.
When the process or set point value crosses the crossover
point, the PID set designated for that region of the oper-
ating range is used to control the percent power being
supplied to the load.
There is a -1° hysteresis for each crossover. A rising tem-
perature will change PID sets at the crossover value. A
falling temperature will change PID sets at the crossover
value -1°.
Location in software: Operations Page > Edit PID > PID
Crossover x (1 to 4).
Figure 7.8a — Multiple PID Sets.
Range High = 1,500
°
F
Range Low = 32
°
F
Operating Range PID Set 5
Operating Range PID Set 4
Operating Range PID Set 3
Operating Range PID Set 2
Operating Range PID Set 1
PID Cross 4 to 5
1,250
°
F
PID Cross 3 to 4
1,000
°
F
PID Cross 2 to 3
600
°
F
PID Cross 1 to 2
300
°
F
Burst Fire (variable-time base)
Burst firing provides even output power with the lowest
level of noise generation (RFI). Burst fire is the preferred
method for controlling a resistive load, providing a very
short time base for longer heater life.
The controller determines when the ac sine wave will
cross the 0-volts point, then switches the load on or off
only at this point, minimizing RFI.
Location in software: Setup Page > Control Output x (1A
or 1B).
Figure 7.8b — Burst Fire.
66% output
2 ON, 1 OFF
50% output
1 ON, 1 OFF
100% output
10 ON, 0 OFF