The auto/off/on option is a very good one. We have used it the past two years and it is very useful. I did it this year by using a two-position rotary switch for the Auto/Off selection. (The rotary switch was solely for looks. A toggle switch works fine.) Use a momentary pushbutton for the On function. This is useful if you lose a pressure switch (which I have never had happen) and also for testing things in the pits. If you are testing out the drive train and don't want your pump coming on every 20 seconds you can switch it to off. You will also want to use a momentary switch for the On function so you do not inadvertantly run the pump all the time. Check out our control system
here. This is the code I use for the OI pump control:
if sw_pump_auto = 0 then end_override: 'OI Pump Switch set to Automatic (UP position)
if sw_pump_on = 1 then run_pump: 'OI Pump ON Override Switch is pressed
pump_on = 0 'OI Pump Switch is Off
goto end_override:
run_pump:
pump_on = 1
goto end_override:
end_override:
As far as one pressure switch or two we started this year with two and decided to go with one for weight. (Hey, 15 lbs over with cause desperate measures.) Regardless, we have noticed no change in performance. Here is the code we use for the one pressure switch control:
'Pressure Switch Program adapted from David Mittelman
'This program will allow us to bring the pressure up to 120psig
'and at the same time not overwork the pump
'For this program to work to variables need to be declared and have the following values:
'lastpressure = 1
'pneum_counter = 0
relay1_rev = 0
if pressure_115=0 then switchopen: 'Is the switch closed right now?
pump_on = 1 'compressor on
goto endroute: 'goto A
switchopen:
if lastpressure=0 then nochange: 'Was the switch closed before?
pneum_counter = 0 'reset counter
goto endroute: 'goto A
nochange:
if pump_on=0 then endroute: 'Is the compressor even on?
if pneum_counter < 220 then pumpitup: 'Is the counter equal to the time?
pump_on=0 'compressor off
goto endroute: 'goto A
pumpitup:
pneum_counter = pneum_counter + 1 'increments counter
endroute: 'A
lastpressure = pressure_115 'lastpressure = Switch value
I hope this helps. Any questions, post them here.