pt104 output

Post general discussions on using our drivers to write your own software here
Post Reply
Erik

pt104 output

Post by Erik »

When I start converting from the pt104 unit what will the 5 bytes that the pt104 sends back to me contain?

The first byte contains the channel number and the measurement number.

The second byte is in msb.

What do byte 3-5 contain?

Best regards,
Erik

Sarah

Post by Sarah »

Hi

Thank you for your post.

You can find full information on the bytes that the PT104 sends in the PT104 help manual under "Protocol Information".

Hope this helps

Best Regards

Erik

Post by Erik »

Thank you.

One more question about the output when reading the temperature:

What does the manual mean when it says (p. 18 ) :

Code: Select all

2-5 reading data: byte 2 is msb
    0x20000000 = 0
    0xE0000000 = max
Should the number I get from the unit be subtracted with 0x20000000?
What is the max value reffering to?

Best regards,
Erik

Sarah

Post by Sarah »

Hi

Thank you for your post.

What you need to do is cast 2 to 5 as a type long, but with byte 2 as the most significant byte (msb).

Hope this helps

Best Regards

Erik

Post by Erik »

Thank you for your answer. But I still don't get it.

Code: Select all

    0x20000000 = 0
    0xE0000000 = max
What does this mean?

Guest

Post by Guest »

Why is this information only available in the pt104.hlp file and not in the manual?

Code: Select all

To calculate a resistance

Read the eeprom to obtain the calibration information for the channels

Take measurement 0, 1, 2 and 3 on a channel.

Then 

result = (channel calibration * (measurement 3 - measurement 2)) / (measurement 1 - measurement 0)

To convert to a resistance divide result by 1000000.0
This would have saved me alot of time.

/Erik

Flovic

pt104 output: meaning of the measurements?

Post by Flovic »

Hello,

I am busy writing a linux driver to read out temperatures from PT-100 3-wires. I am currently using the idea of the manual (ResistanceE6 = Calib*((Meas3-Meas2)/(Meas1-Meas0)), but I see an offset in the results for some sensors that is not present when using your Windows-driver.

What do the 4 measurements of each channel represent? According to the values I get, it doesn't seem to be the voltage of the 4 input pins, or am I mistaken...?

Why is there a possibility in your software to set "3-wires" or "4-wires"? What is the difference in your Windows-driver between setting "3-wires" or "4-wires"? Do you also use the (ResistanceE6 = Calib*((Meas3-Meas2)/(Meas1-Meas0))?

Thanks for your help,
Flovic

ziko
Advanced User
Advanced User
Posts: 1705
Joined: Fri Dec 01, 2006 10:03 am
Location: St Neots

Post by ziko »

Hi and thank you for your post,

Please have a look at this link, this will answer all your problems.

http://www.picotech.com/support/viewtop ... highlight=

Kind regards
Ziko

Technical Specialist

Post Reply