Programming help

[simon.007]

Hi,
If I would like the CO2 to be on during the day 9am and the PH is greater then 8.36 and off after 20:00 is the programming correct?


If Time > 9:00 Then CO2 On
If pH > 08.36 Then CO2 ON
If pH < 08.34 Then CO2 OFF
If Time > 20:01 Then CO2 OFF

Thanks in advance.

Simon

 

[clp]

Your program is going to be interpreted as if it was written like this since time statements execute first no matter where they are in the program:

If Time > 9:00 Then CO2 On
If Time > 20:01 Then CO2 OFF
If pH > 08.36 Then CO2 ON
If pH < 08.34 Then CO2 OFF

Statements that come latter in the program have higher priority, so if the pH is ever above 8.36 then the CO2 will turn on even if it is outside the time range. I don't think you want this.

Here is what I think you want:

If Time > 9:00 Then CO2 On
If Time > 20:01 Then CO2 OFF
If pH < 08.36 Then CO2 OFF
Max Change 020 M Then CO2 OFF

With these statements the CO2 can only come on during the time range and when the pH is too low. The Max Change statement keeps CO2 from turn on/off multiple times if the pH is oscillating between 8.36 and 8.35.

Curt