Dwyer 8600 - Manual (Page 11)

December, 1998 Page 11 949-1277-3
THE HOME DISPLAY
The home display is the normal display while the control is operating. If no
errors or functions are active, the HOME display will indicate the Process
Variable (the temperature, pressure, flow, RH, etc., that is being measured)
on the top display and the Set Variable (Set Point 1) on the bottom.
Items that can change the HOME display are the Auto/Manual function, the
Run/Hold function, the Prog function, the PCtO function, and any error
message. Description of these special displays follow.
If the Auto/Manual key is pressed, the Manual indicator lights, and the home
display is changed. The upper display continues to show the Process
Variable (PV), but the lower display changes to show the percentage of
output in tenths of a percent to 99.9% (0.0 to 99.9), or 100 if 100%. The
display digit to the right of the number shows a flashing letter
o
to indicate
that the value displayed is no longer the SV, but percent output. The SP2
output is indicated by the use of an overline on the letter
õ
. Access to the
SP2 value is done by the INDEX key. See Auto/Manual Operation on Page
13 for further information.
If Prog is turned On, the HOME display changes the SV display from SP1
to the Present Set Variable as calculated by the Ramp/Soak Programmer
function. See Programming and Operation for Ramp/Soak Feature below
for more information.
If PCtO (Secondary Menu) is turned On, the lower display changes to show
the active percentage of output as required to maintain SP1. The display
is similar to the Auto/Manual display above, except that the letter indicators
do not flash, and the output is displayed in whole percentages of output, not
in tenths of a percent. If the control has both SP1 and SP2, the lower display
will alternate between the SP1 percent output and the SP2 percent output.
Error messages are listed on Page 35.
PROGRAMMING AND OPERATION FOR RAMP / SOAK
FEATURE
The ramp / soak feature offers a great deal of flexibility by allowing changes
in the set point to be made over a predetermined period of time. Dwell times
can be programmed, and the alarm output relays can be programmed to
open or close during any of the segments.
Theory of Operation
The 8600 Series controls offer a very simple approach to programming a
ramp. Rather than requiring the operator to calculate an approach rate
(usually in degrees per minute), the 8600 does the calculation internally.