On 2013-12-08, RogerN wrote:
"Ignoramus31823" wrote in message
...

On 2013-12-07, RogerN wrote:
"Ignoramus5722" wrote in message
...

snip

For this, assuming the compressor starts at or below 90PSI and Stops at
or
greater than 125 PSI.

Valve = Primary_Tank_PSI Secondary_Tank_PSI OR Primary_Tank_PSI 120
//
Valve ON when secondary can help or when primary is near full

Compressor = (Compressor AND Primary_Tank_PSI 125) OR (NOT Compressor
and
Primary_Tank_PSI = 90) // Compressor turns ON at 90 PSI and OFF at 125
PSI.

RogerN



Roger, this is what I may end up doing, except no software is
needed. All that is needed is a compressor pressure switch and a NC
relay.

i

With a little additional programming, the pressure transducer information
could be used to get a little more run time at pressure. For example you
could measure the rate of pressure change when the compressor is running but
no air is being used. The rate of change for the compressor can be compared
to current rate of change of air usage. If air is being used as fast as or
faster than what the compressor can keep up, you can turn in on before 90
PSI to give you more run time at pressure than you'd get waiting until 90
PSI to turn it on. Not sure that it would help you much but set points that
vary with demand can give you more air.

I do not think that I can get more run time with that, and I
definitely do not see the benefit worth diong software, adding
computer etc.

i