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duxxx001
Active User
Joined: 07 Jun 2005
Posts: 6
Location: Edinburgh
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 Posted: Thu Jun 16, 2005 1:06 pm Post subject: TC-08 (USB): Reading temperature in Kelvins problem |
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I have a problem getting right temperature in Kelvins from the driver for the last channel (8.). Cold Junction temperature and first seven channels work OK, but 8. channel always output temperature in degrees Celsius.
Here is the C code that verifies that:
| Code: | /**************************************************************************
* C program for reading temperatures from TC-08 (USB) device in Kelvins
* author: Dusan P Djurdjevic, Edinburgh UNI, 2005.
***************************************************************************/
#include <stdio.h>
#include "usbtc08.h"
#define TC_TYPE_K 'K'
int main()
{
short hTC08;
int i;
float buf1[10], buf2[10];
short overflow;
// open unit
hTC08 = usb_tc08_open_unit ();
// check if everything OK
if (hTC08 <= 0)
{
printf("Error Code: %d\n",usb_tc08_get_last_error (0));
return(99);
}
// set channels
for (i=0; i<=8; i++) usb_tc08_set_channel (hTC08, i, TC_TYPE_K);
// read temperature in Celsius Kelvin
usb_tc08_get_single(hTC08, buf1, &overflow,USBTC08_UNITS_CENTIGRADE);
usb_tc08_get_single(hTC08, buf2, &overflow,USBTC08_UNITS_KELVIN);
// write output
printf("%10s %10s %10s\n","Channel No","C","K");
for (i=0; i<=8; i++) printf("%-10d %10.3f %10.3f\n", i, buf1[i], buf2[i]);
} |
Results from the program: | Code: | D:\Projects\Experiments_SEE\Driver\Drivers\Win32>kelvin_problem.exe
Channel No C K
0 25.757 298.757
1 25.467 298.595
2 25.544 298.555
3 25.695 298.672
4 25.743 298.643
5 25.503 298.444
6 25.698 298.621
7 25.312 298.235
8 25.772 25.728 |
This problem does not appear if I use other Temperature units (Rankine or Fahrenheit).
My feeling is that problem is in the driver, where temperature conversion takes place, and if ther is a loop, upper boundary of that loop should be increased by 1. |
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Sarah
Guest
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| Posted: Tue Jun 21, 2005 11:40 am Post subject: |
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Hi
Thank you for your post.
We have investigated this and found that there was an error in the driver. We have corrected this and if you email tech@picotech.com requesting a copy then we will send it to you.
Best Regards |
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duxxx001
Active User
Joined: 07 Jun 2005
Posts: 6
Location: Edinburgh
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| Posted: Fri Jul 01, 2005 8:41 am Post subject: |
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| Sarah wrote: |
We have investigated this and found that there was an error in the driver. We have corrected this and if you email tech@picotech.com requesting a copy then we will send it to you. |
Many Thanks Sarah.
Actually it would be of great help if the source code of the driver is available. In that case, more developers could be involved, and maintaining of such piece of software would be much easier.
Regards,
Dusan |
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Sarah
Guest
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| Posted: Fri Jul 01, 2005 9:24 am Post subject: |
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Hi Dusan
Thank you for your post.
I do see your point, however Pico do not release the source code for their drivers. If you see any potential programming errors with them then let us know and we will investigate for you.
Best Regards |
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