It would help to know 3 pieces of information:
1. Which physical ports on the TC4 are the probes connected to?
2. Which probe, if either, do you think is "right"?
3. Are you sure that the probes are actually measuring the same thing? In
my roaster, there will be large (and correct) differences between probe
readings based on placement of the probe within the roasting chamber.
Pending your reply, I can think of a few possibilities:
1. Perhaps your Arduino is programmed to expect different types of
thermocouples on the 4 TC4 input ports. By modification of the user.h
file associated with aArtisan.ino you can individually select either type
K, type J, or type T on the ports. The default is type K. If there is a
mismatch between actual thermocouple type and expected type then you will
see exactly this type of linear variation of readings.
2. Perhaps there are ground loop effects in play. If one of the probes is
grounded and the other is not then you might expect different readings when
the Arduino is powered by a non-isolated USB port. This effect would
generally not be present with a fully isolated instrument.
3. It is rare, but self-heating effects from the probes themselves can
possibly throw off readings. This could happen if you have relatively
short, heavy lead wires between the probe and the TC4. In this scenario
the probe wires themselves can conduct heat all the way back to the
terminals on the TC4 causing the terminal hardware to heat up. Because all
4 input ports share the same ambient temperature sensor then local heating
of the input terminal hardware could throw things off. (I would classify
this as very unlikely, however).
On Mon, Feb 8, 2016 at 2:14 AM, Marko Luther <marko.luther(a)gmx.net> wrote:
On 08.02.2016, at 05:37, Dustin Betterly
I'm having an issue with only one type of probe, the alt BT probe, and
not sure why. Eric S. was kind enough to send me a replacement, but I
get the same results with the replacement. The reading of the alt BT probe
gradually gets further and further apart from the standard BT probe as the
temp gets higher. So at 100 degrees, the alt bt and bt read the same. At
200, they start to drift by about 25 degrees, by 300, 75 degrees (Those are
rough numbers..). I'm not sure why its doing this, but I'd really like to
get the alt bt probe working so I can do smaller batches.
Things I've tried:
1. I plugged both probes into my Thermoworks Blutherm duo and the
exactly the same at all temperatures.
2. I used the serial monitor to get readings, and they were similar to
the artisan software.
So here you looked at the raw values reported by the TC4, right. So might
it then be an issue of the TC4 or its firmware? In that case you might ask
Jim (TC4) for support. It might be something wrong with the averaging on
the TC4 for that channel (unlikely).
3. Right now I use k-type female sockets, so I tried hard wiring and
4. Tried different ports, same results.
Would anyone have any ideas as to why this is happening or what else I
can do to
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