Issue with Markers from COM port


Issue with Markers from COM port

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jcappsiv
jcappsiv
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Hi I am communicating with a fNIRS device via COM port and it seems that using inquist or the serial port monitortool to send bytes my device always detects it as different byte... and sometime it changes.... I'll send bytes of 251 and it registers as 230 or some other number.

I went back and checked it wasn't my settings... as my e-prime programs send markers just fine. 
Then I checked inquist via another computer... same issue.

 Any ideas?


Thanks,
John
Dave
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jcappsiv - Friday, November 9, 2018
Hi I am communicating with a fNIRS device via COM port and it seems that using inquist or the serial port monitortool to send bytes my device always detects it as different byte... and sometime it changes.... I'll send bytes of 251 and it registers as 230 or some other number.

I went back and checked it wasn't my settings... as my e-prime programs send markers just fine. 
Then I checked inquist via another computer... same issue.

 Any ideas?


Thanks,
John

Doing some testing, there seems to be an issue as soon as the highest bit in the byte sent is set. I.e. values between

0 (decimal; 00000000 as 8 bit binary value)

and

127 (decimal; 01111111 as 8 bit binary value)

are sent correctly, but as soon as the eigth bit is set, i.e. from

128 (decimal; 10000000 as 8 bit binary value)

on, things get weird, although I'm not yet sure why. Would that correspond to what you're seeing or are you getting something else?

GO


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