toddp65

I'm not sure what you're getting at... However: Micrologix 1400 using RSLogix 500 software The engineering firm who wrote this narrative/Description is the lead of the project.  I have to program the PLC and we have a contractor doing the Ignition programming off  my code for the SCADA program (pH equalization/Leveling project for wastewater in a brewery.  Would it be their responsibility to create the Lookup table?  I've never done one such as this when your comparing pH levels and you're supposed to create a proportion time based upon different between set point and current variable. This time base (0-300) is the time a solenoid valve is closed that operates a chemical dosing pump (Acid or Base).  

Panic...are you referring to me?  what do you mean secretive?  I don't have a data sheet or a table.  The narrative provided by the engineering firm  is all I have to work with.  This is all they provided me :   In the Dosing mode they specify " The valve closed time shall be based on a Lookup table such that when the difference between the measure pH and the pH set point is large the Valve Closed time shall be shorter and when the difference between the measured pH and pH set point is small, the Valve Closed time shall be longer.   When I just did a quick SCP in the code and changed the float input, the time base changed proportionately...that said,  it functionally linearly but as you mentioned pH scale isn't linear.   PcmMacartney--I'll look into that option     

Thanks, panic Mode What if the variable is pH. 7.1 to 14. Since the first number is a decimal I'm assuming all of the variables need to continue (7.2, 7 .3, .7.4, etc. ) and time being the unknown (range 0-300--so 7.1=0 and 14=300). I can run a SCP with those as min and max but I'm not sure if that's what they want.  

Joe--thanks!   Could you give some background on this project?  ex, what are you integers representing?  When i hear the term lookup table I'm thinking of a graphed table converted to a data table. 

So I'm somewhat at a loss here during my task to create a MLX 1400 project for an Ignition/SCADA wastewater pH leveling system. Our chemical dosing pumps are solenoid controlled air diaphragm pumps and the specify two different modes of operation--Dosing and  reaction. In the Dosing mode they specify " The valve closed time shall be based on a Lookup table such that when the difference between the measure pH and the pH set point is large the Valve Closed time shall be shorter and when the difference between the measured pH and pH set point is small, the Valve Closed time shall be longer." I'm not sure how to create said lookup table.  I've seen references online to writing one in excel and uploading it to using indirect addressing and status instructions.   Thoughts anyone?