Inaccurate Cycle Time on Auber SYL-2352 PIDs

I have three 2352 PIDs and the cycle time is way high on all three.

I set t=2, which should make the cycle time be 2 seconds, but the actual cycle time vary between the three PIDs and they are all way high.
HLT: 3.0 sec, RIMS: 4.4 sec, BK: 7.3 sec.
Why?

A good way to measure the cycle time is to set the PID to manual and 3% output. It is then easy to time the LED blips with a stop watch.

Anyone else notice this problem?

Has anyone successfully disassembled one of these PIDs?

I don't think it really matters. Use auto-tune and the PID learns what to do in relation to it's specific cycle time. The only place where it really makes a difference is in a RIMS tube. For that, I set mine to 0, I think, so that it won't try to stay on too long. I know it's harder on the SSR, but SSRs are cheap. I'd rather replace an SSR than burn wort.

As for manual mode, once you know where you need to set it at for manual, then the cycle time is irrelevant as well...

This is just my understanding an my opinion.

Right, the cycle time matters most in the RIMS tube. It matters to some extent in the BK as well because I can see the boil pulsing on and off, which I don't like. I think I will reshuffle the PIDs according to cycle time priority.

According to the manual, the minimum cycle time is 2 seconds. I noticed, though, that it is possible to set a lower number than 2, but I don't know what happens then.

As for the pulsing, maybe set the Proportional Constant (p I think) to 1 as recommended in this thread.

https://www.homebrewtalk.com/f11/pid-cycle-time-help-96548

Quaffer said:

According to the manual, the minimum cycle time is 2 seconds.

Click to expand...

The reason for a 2 second minimum is a PID's output is actually a % value of the cycle time. At the minimum output of 1%, the total on time is 20ms (.01 * 2000ms). A single cycle of AC is 16.7ms. As the SSRs we typically use are zero crossing, there's no point in going any lower as a single cycle of AC is the minimum the SSR can output.

Follow the PID manual's instructions and set the cycle time to 2 seconds or greater.

bbognerks said:

As for the pulsing, maybe set the Proportional Constant (p I think) to 1 as recommended in this thread.

https://www.homebrewtalk.com/f11/pid-cycle-time-help-96548

Click to expand...

Thanks for that link, it explains a lot! I will try it now.

jkarp said:

The reason for a 2 second minimum is a PID's output is actually a % value of the cycle time. At the minimum output of 1%, the total on time is 20ms (.01 * 2000ms). A single cycle of AC is 16.7ms. As the SSRs we typically use are zero crossing, there's no point in going any lower as a single cycle of AC is the minimum the SSR can output.

Follow the PID manual's instructions and set the cycle time to 2 seconds or greater.

Click to expand...

Yes, I have it set to 2 seconds, but cannot acheive 2 seconds actual cycle time. Apparently the P setting somehow influences the minimum cycle time, although it makes no sense to me.

bbognerks said:

As for the pulsing, maybe set the Proportional Constant (p I think) to 1 as recommended in this thread.

https://www.homebrewtalk.com/f11/pid-cycle-time-help-96548

Click to expand...

That was it! For some reason the P setting influences the minimum cycle time. I reduced P to 1 as the thread suggested and now the cycle time is 2 seconds, just like I expected it to be from the beginning.

For the BK I will simply set P=1 and t=2 and use it in manual mode. As for the RIMS tube, I will need to experiment a little with the PID parameters to find settings that both holds the temperature well and allows a 2 second cycle time.

Thanks again for that link.

Theres another change you can make, I think with the Hy that can allow a 1 second cycle time. I cant remember exactly what it was but mine is set so that if I set it to 50% the light is on for half a second and off for half a second.

P is very odd on the 2352. Different than other "normal" PIDs.