PID display modules

[TrickyDick]

Howdy,

I'm using three to show temps and setpoints for my BCS controlled fermentation setup.
It appears that that the displays only show the current temp but not the setpoint temp.
Is this a known issue or have I screwed something up?

TD

[JonW]

The set temp will only display when the process is running. Current temp displays all the time.

[TrickyDick]

On my setup, the set temp is not being displayed while a process is running.

Also, the current temp doesn't seem to be accurate with what shows on the WebPage interface for the BCS.

I am wondering about this. I am using the BCS460 to control fermentation tank temps and a glycol coolant reservoir temp.
I am using hysteresis with 2 degrees offset on the fermentation tanks and 7 degrees on the coolant.
It seems that on the web interface, the data log graphs show that its keeping temps roughly between -1 to +2 of the set temp. This seems to be great control to me!

Mostly I am not sitting in front of the displays to see if the set temp displays or not when the coolant is circulating to that specific fermentation tank, and by the way, they are called PID displays but I'm not using PID, I'm using hysteresis. At least it should show the correct current temp? My outputs are: a pump, an AC unit, and three ball valves. None of these would benefit from PID I don't think anyway, at least without rapidly cycling the valves, pump or AC unit. The hysteresis seems to be the best in my mind.

At any rate, I'm mostly curious why the current temp isn't accurate with what is shown on the web interface.

Thanks

TD

[JonW]

Hysteresis is fine and the LED displays should display your set temps using that method.

What firmware version are you running? What are the settings you have in your system settings for the displays? Has each display been set to a unique address?

[TrickyDick]

I do have the modules set to unique addresses.
As far as other settings would you like to take a peek? I can send you the IP and password to snoop around but would rather not post publicly.

I suppose one thing I might do is calibrate the temp probes. Is there a procedure for calibration on all the temp probes?

Thanks!

TD

[JonW]

I'd be happy to take a quick look. You can PM me the credentials. It could be Monday though before I have an opportunity to take a look.

[TrickyDick]

So today I did a little investigation.

Recorded the temperatures of all three insulated tanks, each filled with 11-12 gallons water, and been sitting in my basement for several days - no cooling other than house AC unit cycling off - SWMBO has t-stat set at 78 (Its a constant war of wills). So after setting the t-stat to 75 degrees, I head into basement with my Thermapen. For those who don't know, a Thermapen is a highly accurate thermometer for cooking, and its one of the only thermometers I've ever trusted.

Three temps on each tank: PID Display, BCS control panel, Thermapen.
If I was cool, I'd have made a table and uploaded it, but I'm not that cool.

In order given above for three temps:
Tank1: 76.7, 77.4, 77 (delta T=0.7)
Tank2: 77.1, 77.4, 77 (dT=0.3)
Tank3: 76.9, 77.2, 77 (dT=0.3)

So what I see here is that the Thermapen and BCS are essentially concordant readings. The delta T between any two readings is pretty close. I suppose for fermentation this is pretty close. Tank one has a bit larger delta of 0.7 degrees comparing the PID and the BCS. If they could all round themselves to nearest integer, all would be happy. What I am wondering however, is why this is like it is? I don't know the accuracy or precision of the thermocouple, so there's that.

I will need to see if the deltas are similar when at operating temps instead of room temps.

TD

[oakbarn]

From my understanding, the PID Display module (7 Segment Display) is just a repeater of the BCS. I would say that the PID Display modules currently control nothing and would simply repeat the probes via I2C communications. The delta could be delay or EMI on the line. The BCS is using the "internal" temps for any control and the PID Displays are for convenience. Brewer's Hardware will be selling the PID Display module (7 Segment Display) in the near future. I have had such issues with mine that I went with a Chomecast into a TV and just cast the Temp Display from my browser. The TV sits above my brew area and I can read it. Hopefully 4.0 will have the ability for a single gauge full screen so I can read it from my Brew Recliner!

[brahn]

The values for the LED displays and the temp displays on the BCS web page come from the same internal values. The temp displays on the BCS web interface can update more often than the LED displays, which are updated every 2 seconds.

I didn't see an answer to which firmware version you are using. 3.7.0 has major bugs in the LED display code, which was completely rewritten in 3.7.1.