Watlow Series 920 Microprocessor-Based Ramping Control - Manual (Page 37)

Event Outputs
Another feature of the Series 920 is its capability for two event outputs. An
“event output” is simply a pre-programmed ON/OFF event per program step.
The event may turn any number of peripheral devices ON or OFF to
assist you in
controlling your process, system or environment.
For instance, in an environmental chamber, you might wish to circulate air at a
given time in your program for one or more steps. You might want to turn lights
ON or OFF, or signals, or lock out your humidifier, or you could activate a video
recorder.
EV1 and EV2 will not be visible under the SYSTEM menu until you SETUP AUX1
and AUX2 as events (EV).
Enter the SETUP menu, and enter ACCESS (5). This is the SPCLFUNK (Spe-
cial Function) parameter. Press the MODE key until you reach the AUX1 pa-
rameter and press ENTER. The default for AUX1 and AUX2 is AL (Alarms).
Change the value to EV (Events) if it hasn’t already been done.
If you return to the SYSTEM menu, EV1 and EV2 will be visible, and can be
turned ON or OFF from here. EV1 and EV2 can also be viewed under the
SETPOINT parameter in the PROGRAM menu.
If the events are programmed for one step and left unprogrammed for the next
step, the events will maintain the last programmed status.
These event outputs are mechanical relays rated at 6 amps up to 240VAC
Guaranteed Soak
The Series 920 Guaranteed Soak (GS) feature insures that the process tempera-
ture tracks a programmed ramp. The Guaranteed Soak acts as a deviation
alarm. The program clock halts if the ACTUAL temperature exceeds the Guaran-
teed Soak value. At this time the HOLD LED flashesand the clock starts once
the process variable is within the GS deviation value. Programmed in degrees or
process units, GS is in the SETUP menu under ACCESS (5). Entering a value of
(0) disables the Guaranteed Soak function. Figure 28 is an example of the
Guaranteed Soak function.
Temperature
Guaranteed Soak
Programmed Ramp
Window Around Set
Point
Time
Figure 28 -
Guaranteed Soak
(GS) Example
NOTE:
If the program is put
in the HOLD mode
while holding for a
guaranteed soak
and restarted at
another step, the GS
has to be met for the
previous step,
before the program
can continue.
How To Program the Series 920, Chapter 6 WATLOW Series 920 User’s Manual
37