Getting Temperature Readings into EMC

Some recent discussion on the mailing list (started by me) on getting a couple of temperature readings into a PC (for a smoker) got me to thinking that having temperature monitoring of electrical cabinets or motors available to EMC would be a good thing to have. To be honest there were so many suggestions tossed at me it kinda overwhelmed me a bit. I wanted to get as much opinions as possible on how to do this and if lucky someone has done it all ready so I added this topic here.

My first thought is how can I get the raw temperature data into the PC via the USB port which all recent computer have.

This is one idea that seems to be easy maybe to do...

in my opinion the best device for digitizing a thermocouples milli-volt signal is the MAX6675 IC. This device is great because all you have to do is hook the thermocouple up to it and read the temperature using some SPI interface. I have used these devices with an Arduino (read cheap and easy IO) with EMC and other software. You can read several of these devices using an arduino and I think it is the cheapest way to get a thermocouple signal into a PC.

Anyone familiar with the Arduino and knows what all I might need?

Any thoughts are welcome.

Thanks
John

Mick, That piotech and mccdaq stuff is way out of my league...

PCW, thanks for the link, now we are getting simpler.

John

I've found some thermistor probes that are cost effective and use a 2.5mm jack so that is just a resistor connection to the Uno.

John

Well nothing is as easy as it looks. Seems like the Arduino wants

The ADC is optimized for analog signals with an output impedance of approximately 10 k or less.

and my thermistor measures about 220k ohms at room temperature.

although I found this on the web using the same thermistor and he used a 22k resistor for the voltage divider circuit.

hruska.us/tempmon/

I also found this on using thermistors with the Arduino

web.cecs.pdx.edu/~gerry/class/EAS199B/ho...hermistorArduino.pdf

Now I'm really confused...

John

Peter, Thanks. I'll keep plugging along with this.

John

Hi Rick,

Thanks for the links. I'm trying to use a thermistor that is easy to purchase and cheap like the replacement probes for the ET-73. I've looked at the AD595 and a MAXX one and both seem a good fit for a thermocouple.

My little breakout board has a place to solder on a SOIC chip so if I decide to go that route I think there are some chips that fit that.

John