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strange parallel port behavior - Labview 7, Win XP
eromero
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11-13-2004 06:56 PM
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We have a computer with Win XP...we used the Access Hardware files to be able to write directly to the parallel port. We are controlling a custom relay card. The problem is...every time we start the PC, when we activate bits 4 to 7 (any of them) the bit in question goes on and off exactly eleven times..and with 5 seconds between transitions.
We have a loop that is always writing a 1 to the bit...so...e.g. we put bit 5 in ON State..and five seconds later it goes off..the loop sets it ON again and five seconds later it goes off..again..and again exactly eleven times...the weird thing is that after doing this..everything works very well..until we restart the computer...it does the wird cycle again, eleven times.....
W
e were thinking it might be something related with a printer driver ...or something related but we can´t find the problem...does anybody had this problem before?....anything will help...
(We´ve used the same relay card and software with no problems in other PC´s...not on XP before..but i don´t think that´s the problem.)
We have a loop that is always writing a 1 to the bit...so...e.g. we put bit 5 in ON State..and five seconds later it goes off..the loop sets it ON again and five seconds later it goes off..again..and again exactly eleven times...the weird thing is that after doing this..everything works very well..until we restart the computer...it does the wird cycle again, eleven times.....
W
e were thinking it might be something related with a printer driver ...or something related but we can´t find the problem...does anybody had this problem before?....anything will help...
(We´ve used the same relay card and software with no problems in other PC´s...not on XP before..but i don´t think that´s the problem.)
tbob
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11-15-2004 10:58 AM
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I would not be too hasty in dismissing XP as the problem. XP wants total control of everything. Even after booting up to your normal desktop screen, there are things still going on in the background for a few seconds (which may explain the 11 times). Now this could be a print driver or it could be XP trying to reset the parallel port or a combination of both. I've had troubles using the serial port with XP because it does things differently. Things to try: Go to BIOS setup and make the parallel port standard (not EPP, not ECP). Remove any print drivers that exist. Last resort, replace XP with Win98, then try Win2K.
