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Erik
Guest
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 Posted: Tue Jun 28, 2005 11:12 am Post subject: pt104 output |
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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 |
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Sarah
Guest
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| Posted: Wed Jun 29, 2005 8:16 am Post subject: |
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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 |
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Erik
Guest
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| Posted: Thu Jun 30, 2005 11:36 am Post subject: |
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Thank you.
One more question about the output when reading the temperature:
What does the manual mean when it says (p. 18 ) :
| Code: |
2-5 reading data: byte 2 is msb
0x20000000 = 0
0xE0000000 = max
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Should the number I get from the unit be subtracted with 0x20000000?
What is the max value reffering to?
Best regards,
Erik |
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Sarah
Guest
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| Posted: Fri Jul 01, 2005 10:12 am Post subject: |
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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 |
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Erik
Guest
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| Posted: Mon Jul 04, 2005 7:00 am Post subject: |
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Thank you for your answer. But I still don't get it.
| Code: | 0x20000000 = 0
0xE0000000 = max
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What does this mean? |
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Guest
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| Posted: Tue Jul 05, 2005 6:43 am Post subject: |
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Why is this information only available in the pt104.hlp file and not in the manual?
| Code: | 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 |
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Flovic
Guest
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| Posted: Wed Jan 17, 2007 9:06 am Post subject: pt104 output: meaning of the measurements? |
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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 |
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ziko
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Joined: 01 Dec 2006
Posts: 596
Location: St Neots
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