Fermentation Ramps

[laurelstein]

I'm setting up my controller to manage fermentation temperatures in four separate conicals. This system will include a heating belt and an immersion glycol cooling coil for each of the fermenters. I'm hoping that I just don't fully understand the programming of ramps, but it looks like I can only use one output for a ramp. While for short duration heating ramps (mashout) or cooling ramps (cold crashing), one output will work fine. But for longer more gentle ramps, being able to use 2 outputs to heat or cool as needed to maintain a linear ramp would be really nice.

Here's a scenario for a diacetyl rest: the fermenter is at 48. I want to raise the temp 1 degree every 8 hours until it reaches 57. That's a 72 hour ramp. If the ambient temperature is, say, 48, then only the one output (heating) will be needed. Similarly, if the ambient temperature is 68, then only one output (cooling) will be needed - I assume this works to use a cooling device to slow a heating ramp. But what if the ambient temperature is 54? It will need to be cooled when the ramp schedule is below ambient temperature and heated when above.

I realize that the answer is that this is two separate states. I can pick a midpoint temperature = ambient temperature and switch from using the cooling output to a new state using the heating output when the fermenter temperature gets to ambient temperature. But what if ambient temperature isn't constant? What if during a ramp, the fermenter needs heat, say at night and then needs to cool during the day to stick to a linear change from one set point to another? Can this be designed as two simultaneous processes? If that's the way to do it, I've just exceeded the capacity of the 462 for simultaneous processes, since 4 fermenters and a glycol chiller will need 9 processes.

I'm eager to get educated on different approaches.

[ECC]

Yes, I see your issue. Indeed, currently ramp mode is only able to ramp one setpoint per processes at any given time. Or in other words, since setpoints are hard tied directly to individual outputs, you can only ramp one output. I see where this can be very limiting in a dual-stage configuration.

This shouldn't be to bad to fix in a future update. I can update the ramp to update the new ramp setpoint to multiple outputs. Unfortunately in the meantime, you are going to be limited.

One solution would be to do 'steps' instead of a 'ramp', up to 8 steps per process as that's how many states are available. If you want 1 deg steps over eight hours, program 8 states with 1hr timers and setpoints (for both heat and cool outputs) set in 1deg increments. Its a lot of programming, but will get you the desired result. I'll work to get more outputs in ramp mode.

[laurelstein]

Thanks for the response. One of the great things about this controller is this forum and your quick and informative responses. It greatly increases the value of an already very useful device.

The multi-step approach occurred to me, but I have 4 fermenters that I want to control simultaneously, so I can't tie up the available 8 processes for what I think of as one state in a much longer process. So instead, what I've done is have the main process spawn a second parallel process that runs only during the ramp phase. This second process runs a 48 hour ramp for the heater. The main process has a state with the counterpart ramp also 48 hours long and with the same start and end set points. When the time runs out the second process ends/is killed. I have yet to test this. I assume/hope that two simultaneous processes can use the same temperature input.

The drawback is that this ties up 2/8 processes. Having more than 8 processes, I have taken to saving them and then loading them when I need them. Not the most elegant, but fully functional.

Anyway, I salute your future effort to make it possible for a ramp to have two outputs. I don't know if there is some restriction to the programming, but while you're at it, expanding the functionality to control even more outputs may anticipate future requests.

[bergerrings]

I am looking at buying a BCS for this exact purpose. I plan on using all of the temp inputs:
4 x fermenters
1 x brite tank
1 x cooling
1 x heating
1 x fan control for control box

I was under the impression that one single process could be allocated to each of the above temp probes and that each could have multiple outputs, so if the temp was below (the set point), the heating would turn on and if the temp was above the cooling would turn on. This is a rather old post, has multiple outputs been added yet?
I have also come across this other post that seems to say that this is possible:

2 Stage Control
by rcrabb22 on Thu Jul 01, 2010 11:51 am

Does this state machine seem reasonable for 2 stage control of a fermentation chamber?

Two Stage Ctl
• State 0: Temp +/- Rest. Exit0 timer0 <=0 , initialize timer0 = 10:00 min, goto State 1
• State 1: Hold Temp; Exit0: temp0 > = 68F goto State 2. Exit1: temp <=66 goto State 3
• State 2: Cool; Assert out0, cool source; exit0 temp0 <= 67F goto State 0
• State 3 Heat; Assert out1, heat source; exit0 temp0 >=67F goto State 0

State 0 is for temperature over/under shoot. The heating or cooling source might give off residual temperature influence after shut down so I was giving a rest period for temperatures to equalize and also for compressor rest cycle for cooling source. If the process was restarted after a power hit, I would also want a compressor rest period on process restart

State 1 will use 2 exit conditions to call for either heat or cooling as needed.

The dead zone temperature range (range between heat and cooling) would need to be adjusted for actual performance of the fermentation chamber and temperature probe stability.

Comments?
rcrabb22

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Re: 2 Stage Control
by ECC on Fri Jul 02, 2010 10:14 am

Yes, that looks great.

ECC

Posts: 662
Joined: Fri Sep 12, 2008 2:29 pm

Is this the solution to the original problem? Or are they asking two different questions? From what I can tell, rcabb22 seems to be able to assign multiple outputs, without having to split it across several process, therefor allowing all 8 process to be used independently?

I hope someone can clarify this for me. I was just getting ready start buying all the necessary equipment when I stumbled across this and now I am not sure if the BCS can do what I want.

[ECC]

Yes, every state can control all outputs.

The original poster had a issue with Ramp Mode, a feature that automatically ramps the temperature setpoint in a single state. The previous firmware only allowed the setpoint to be ramped to one output. However this has been expanded in the current firmware to allow ramping a single setpoint to multiple outputs, which makes two-stage control much easier.

rcrabb took a different approach, he used timers and exit conditions to implement a process that used multiple states to get the desired result.

Both methods are fully supported.

[bergerrings]

Ah fantastic!

I had already started purchasing all the necessary equipment (at a substantial cost too) when I came across this post and started to get rather concerned!

As mentioned above, I plan on using the BCS for a fully automated fermentation control system which should be quite rugged and future proof. I will take photo's along the way and post them (if I ever get around to finishing!).
Once this is all done I plan to get another BCS and begin to implement that for a 250-300L brewhouse...long ambitions plans haha

Thanks again,

Damo