Dairy Plant HTST FDVC PLC Program

I'm doing some work on a HTST in a dairy plant. I uploaded the PLC program in the once-sealed FDVC (Flow Divert Valve Controller). This controller has been in use for years in an older plant, and now we are going to use it. I see some issues with the program and was wondering if any of you guys happens to have a FDVC program I could look at to compare. I would think that these programs are somewhat standard from plant to plant. If I'm wrong, please school me on this.

Thanks in advance,
James

I have done a number of these. From my experience, system integrators have their own programs and choice of hardware. The FDVC is only one part of the system. Chart recorders for flow and temperature provide forward permissives. The hardware and programming have to meet the requirements of the state inspector. I can not post any proprietary programs but I can answer any questions you have.

I understand that it is only a part of the system. I guess my specific question is that the FDVC has an output (input to the HTST PLC) for a 10 min CIP timer. However, this output is only on for one scan and this makes no sense to me. The program uses a one second pulse timer and also uses a counter. Each pulse increments the counter one time. The preset is 660, so 660 seconds. The 10 min CIP timer output is only on when the counter is done. When the counter is done it resets, so the output is only on for one scan. This is where my confusion is.

I looked in the HTST program and it is looking at this input as a permissive in several locations, so only being on for a short time will not work.

I don't have the program handy, but maybe I should post it tomorrow because I'm afraid I may have not explained myself very well.

Mine is programmed similarly. I have a 60 second timer which increments a counter. The counter's preset is set for 11. Even though it's called a 10 minute CIP timer, the inspectors like them to be set for 11 minutes. You are right about the output needing to stay on. Mine is programmed to stay on as long as the FDVC is in CIP mode.

I would suggest you change the timer preset to 6000 with time base of 0.01. When timer is done, it resets and increments the counter. There is a natural error each time the timer goes done, it will increment a little past preset due to PLC scan time. Having it go done 11 times instead of 660 will accumulate less error overall.