6551 problems

[hason]

i am useing a pxi 6551 to generate a pulse signal. one channel is

generating

a 20Hz square pulse with a width of 440us. on another channel i am generating a

20Hz

repeting pulse with a width of 127us. the 1st channel pulse is delayed from

the

rising edge of the 2nd channels pulse by 115us. since i started used the rev e

6551

cards, one of the 2 channels have gone bad on multiply different cards. i need help in understanding

what configurations

factors that might kill a channel.

[Ryan_M]

Hason,

The 655x devices have several specification regarding the front end electronics.  Generally for IO abuse scenarios, I would make sure that you're limiting the current draw from a single channel to less than +-50mA and across all channels to less than a total of +-600mA.  Each channel has protection diodes so make sure that you are staying within the protection limits of -2.3V to 6.8V.  If you are within these limits then you should have no problems. 

One other thing you may check is the cable.  It may be that you have a bent pin inside the cable or on your DUT that intermitantly fails across multiple boards.

I would recommend calling NI ((800) 531-5066) for recommendations on trouble shooting your system and potentially repairing your device. 

-Ryan M

[JuanCarlos]

Hi hason,

Could you give us a bit more details on your setup? what is the board interfacing to? are the baords failing in a single system or multiple systems?

Thanks in advnaced.

Juan Carlos

[hason]

the pxi is interfaceing the dut through a virgina panel.  we only have one system

[JuanCarlos]

Another thing that you may want to check is that there are no common mode voltages on the system. Make sure that both the tester and the DUT have the same ground reference. There is a chance that the DUT is not generating any dangerous voltages, but the ground difference is bad enough to damage the device.

I hope this helps.

Juan Carlos