BrianC

I have never used a PID loop before but need to for a project. We have a reservoir tank with oil in it. When motors are running it will heat the oil from room temperature (70° F). Once the temperature starts to rise, I need to activate our cooling system and proportionally control a valve to maintain the temperature at ~95°F. Every example I have seen uses the autotune, but i am not sure how to allow our system to run the autotune to get the correct values. Also, the reservoir will respond very slowly to the changes, so I need to sample time to be 30 seconds to 1 minute between adjustments minimum. Is trying to run the autotune to get all the correct values the best thing to do in my situation, or should I try and manually enter values until I am able to reliably control the temperature? Is there any guidance on figuring out what values to enter for a manual tune? Any help is appreciated.

Great. Thank you for this advice. I appreciate it.

Thank you for the reply Alex. I did not realize the values I put into visilogic would not move over to the PLC on a normal download. I am updating PLC's in the field with the program on an SD card. Is there any way to force these values to the PLC (Other than assigning all 250 ish values to MI's and then writing them to the table) via an SD card? Thanks

I am using a V570 PLC. I have 2 data tables that contain data. One of the tables is 12 columns by 21 rows and the data never changes. The second table is 1 row and 8 columns, and the data does change periodically. I have the table data all written out in visilogic, but after doing a full download to the plc and then going online, the data tables are completely different data from what I just sent to the PLC. There are no write functions to table 1 at all, so I know the data is not being overwritten. Any help is appreciated.

I am taking pressure values from a pump. I need to store the value every time I call a function (.7 seconds) and take the average of the last 7 values. I only care about getting a ~5 second average, then I can forget the numbers. I need to do this for several values, so something reusable would be great. I cannot seem to figure out an easy way to accomplish this. Any help is appreciated.