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Using Roastmaster with a Diedrich IR24  (Read 316 times)

DunlopRoaster

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Hi, I'm new to the forum so I apologize if this is going in the wrong place.

The company I roast with owns a Diedrich IR24. It's an older model ('80s I think?) and all we have is the first generation Siemens Simatic Panel. After describing the benefits that Roastmaster could offer for our development and workflow the owner of our company gave us permission to get RM up and running on our system. Now the question is "how?".

In one sense the ThermaQ blue seems like the simplest option, but then again it would require adding an additional probe (especially since our machine has a K type probe and ThermaQ uses J). I assume that going this route would require drilling into the machine. If there is another way to do this please let me know.

The other primary option I see is Phidgets, which seems like a better long-term solution (since it would also set us up for other software if we desired, like Artisan or even Cropster). My concern is that it looks incredibly complicated to get set up. Other questions:
-Would we be able to somehow "tap in" to our existing K-type thermocouple, or get one with two outputs (not sure what the technical term is)? If not then Phidgets has the same problem that ThermaQ does—the need to drill into the roaster.
-I read somewhere on the forums that Diedrichs already had Phidgets installed... Did I misunderstand this?
-I also notice that our thermocouple has two wires running from it... Is that normal, or does that possibly indicate that it already has two outputs? If so I'll have to look into what the other one is being used for if anything.

I basically need some direction and recommendations for getting this set up. Thanks in advance!

Danny Hall

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Hi

Most folks use this forum for just tech support, so there's not the typical community traffic. Any members with more info...feel free to jump in.

No - you cannot safely "split" or "tap" thermocouple lines. The voltage they carry is extremely small, and the extra impedance would cause the temps to be inaccurate. Since factory thermocouples are utilized in safety functions, you want to avoid that at all costs.

But…that appears to be a dual tip thermocouple. One set of leads should be wired to the roaster electronics. The other set may be already wired to a Phidgets Temperature Sensor (from a previous owner maybe). See if you can trace those wires and find the temperature sensor - either a 1 port or 4 port (pics attached). If so, the temp sensor may be enclosed in a clear acrylic case, with an open port for a USB cable.

If that's the case, Roastmaster can talk to the Phidget Temperature Sensor, but since there is no USB port in iOS, you need a WiFi "host" to send the signals wirelessly. The Phidget SBC3 is a good choice.

If you're unsure, I'd give Diedrich a call and ask for clarification. There's a good chance that one set of leads would be free for data logging - regardless of the hardware installed. So, if there's no Phidgets Temperature Sensor already installed, you may still be able to use that probe without drilling a new one.

Also - you have it backwards - the ThermaQ Blue only supports K types (not J). So, if the second set of leads is free, and the probe is a K type, you could opt for that for direct Bluetooth connection.

Keep me posted, and let me know if you have other questions in the mean time.

Danny

DunlopRoaster

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Awesome. That's a lot of really helpful information!

I don't know why I had it in my head that ThermaQ was J... I could have sworn I saw that somewhere, but now I definitely see it says K on their site. Very cool. I'm going to try to find where that lead goes in the morning... Thanks again for your help!

DunlopRoaster

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UPDATE: So I finally took the side of the machine off and did some investigation (I have pictures if they are needed). Unfortunately there is no Phidgets installed. One of the probe wires is going to the Siemens computer and the other is going to the "high limit" (which, from what I understand, shuts the machine off if the temperature exceeds 485). According to Diedrich support however, I still do not need to add an additional probe, but can "jumper of the high limit". I asked for clarification on how to do this, but didn't get a response. Do you have any suggestions here, or know where I can go do get help? Am I supposed to somehow "tap into" the probe going into the high limit, or somehow connect something to the high limit itself? Thanks for any help you can provide!

Danny Hall

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Sorry I didn't get back sooner. I'm prepping the next update for beta and got bogged down last week.

Any time you introduce impedance into the path of a thermocouple, it has the potential to make the voltage drift. I'd assume their line of thinking is something along the lines of "if the hi limit shutoff is, say 700°, and impedance causes that to drift +- 30°, it's still within operating parameters". Again, this is just a guess.

Truthfully...do people split thermocouples without adverse effect? Yes they do. Do I advise it? No, I don't. But, for the sake of argument, you'd at least have a "control" value level, since it's a dual tip TC. I assume there's a readout for the primary TC via the Siemens controller, right? If you did jumper off the hi limit, you should be able to tell how much imprudence has been introduced by virtue of what the Siemens reports and what Roastmaster reports.

I'd be interested to know how that Siemens works. I just introduced an opensource WiFi protocol in a recent update for RM, and am introducing a companion Bluetooth LE version in the coming update. My hope is that these controllers can be retrofitted with Phidget-like hardware or accessed directly with USB to then broadcast readings via one of these protocols. That's not an immediate option, but it might eventually open up a lot of older roasters to data logging without breaking out the drill to install a new TC, which of course is always an option, though understandably probably not the route you want to take.

Have you heard anything else from Diedrich?

DunlopRoaster

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Thank you for your help. Yes there is a read out for the TC on the Siemens. What you say about the Seimens providing a "control" makes a lot of sense. In your understanding, is the variance between the two read outs (if indeed there is one) going to be a set amount of degrees or would it be a percentage off (meaning higher temperatures will produce a higher difference)?

If we do decide to split the wire going into the high limit, how should we go about this? Can you point to any tutorials? Would you recommend hiring an electrician?

At this point our plan is to install the ThermaQ.

Danny Hall

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Hmmmm - I would guess that variances would present in a differential fashion, i.e. changing as a factor/percentage of the temperature.

A thermocouple's voltage is generated not at the tip, but in the wire itself - along the gradient of temperature change as it cools before reaching the cold-junction measurement located in the electronics of the probe hardware. My gut tells me it would be best to split wires as far from that gradient as possible - in other words, as far from the tip as possible. but - I'm sorry, I do not know this for sure. If you wanted to know how to write a programatic equation to measure that, I'm your man. But, on the electrical side of it - I think you'll find better sources of input than me. ;) An electrician might be a good idea - someone with some engineering knowledge.

If you were able to set up a call with Diedrich, I'd be happy to jump on the call with you. Let me know.