Hello orionsbelt0
Did you find a solution for connecting two arduinos over a long distance ?
I would be interested in such solution too.

José

Thanks for the reply
Today I figure out that something is wrong, maybe with the max31855.
I will check and get back with news.

Jose

I am using a shield with the MAX31855 with the library from adafruit with my arduino duemilanove.
Using the library example "serialthermocouple" I have measurments of the internal temp of the max31855 about 15 degrees higher than it is supost to be
Using a mixure of water and ice that has a temp o 0º I get measurments of the temp os the thermocouple about 15 ºc.
Does this means my shield is broken ? Or am I doing something wrong ?

Thanks in advance

José

The 1º accuracy was an example. I can work with up to 5º.

José

Hello
I have a burning oven that I need to measure the temp inside. Its located about 8-10 metters away from my arduino mega.
I need a sensor that is able to measure temperatures up to 500 º C with an error of 1 º.
The sensor is not in contact with fire, its inside a metal probe filled with motor oil.
I already tried an thermocouple with the max6675 but it didnt work. The max 6675 works with the SPI interface and this is not design to work with sunch long distances of cable.
So can you please sugest an alternative for this conditions ?
I would apreciate it.

Thanks

José

Hello
I am back to testing.
I am using a cat5 cable to monitor the burning chanber.
Not just for the max6675 but also two DS18S20, one rele and one servo motor.
The cables i was using for the max were:
+5V-Green
Ground- Green and white
SCK- Orange
CS- Orange and white
SO- Blue
With this configuration the code from post #63 was not running.
Today I exchange the Blue and the Orange/White wires and I got this result

Code:

Starting SD..fail
Starting w5100..192.168.1.96
Setup complete
14.0
13.50
14.0
...

So i belive the problem is the twisted wires inside the cat5 cable.
Could this be the reason ?
If i use only one wire from each twisted pair could this solv my problem ?

Jose

Ok
Using the cable again I get bad results.
Do you think the problem is because I am using cat5 network cable ?
Could the twisted pairs explain my strange behaviours ?

Jose

Yes the prob is at room temp, next to the mega.

Looking at the code from post #63 I noticed that you disable the we 5100 after you start it, but you dont do that for the pin from the sd card. Then you start mesuring the max values. Shouldn't youu disable the sd card pin first in order to use the SPI bus for the max ?

José

Hi
Sucess

I removed the board from the box where I had instaled it and all connections to it.
Then connected directly to the mega and with the code from post #63 I get

Starting SD..ok
Starting w5100..192.168.1.96
Setup complete
23.50
23.25
22.50
...

So here are the possibilities for the problem I was having.
-Long wires
-Some wire bronken since the cable was not new.
-Some interference from the DS18S20 sensor.
-Something else...

But now I can move foward and with trial and error find out what I was doing wrong.

Back to my early posts to use all three SPI devices together, I need to disable the other two in order to use one .
Am I right ?
To connect the max I have to use these ports or can I use any port I want ?

José

Hello
With the code from post #63 I have 3.24v between so and ground. Is this ok ?

José

Ps. For further testing I will have to completly disconnect the max and because is already night here I have to wait for the weekend.

Not sure if I understand what you mean.
I do not have an o-scope its on my shopping list. By the way may you sugest a good o-scope for a beginner ?

Connect the voltmeter to measure voltage at SO on the max

Between the So and ground right ?

connect the CS line to 5v

Directly or with the resistor ?

The MISO pin on the max should be high impedance at this point.

What do yo mean by high impedance ?

José

Hello
Sorry for my silence but my litle girl is not been so well.
Today I checked the cable, there is a connection in the meadle, and the results were the same.
Tomorow I will check the board. It was me you made the connections to the MAX6675 IC and there may be a short circuit somewhere.
I will  check the voltage as you sugested.

José

I just remember I have an arduino duemilanove and tomorow I will try to use it next to the sensor do avoid the wire being so long.
I will post the results then.

José

Hi
No Luck
No sd card and no IP.

José

Sure.
At this moment I am whilling to try anything.
By the way whats the problem of having low speed SPI ?

José