NI-6534 stopping DELL optiplex from powering up

[ChrisHogg]

We have been using Ni-6534 high speed digital IO cards for a number of years now. Recently we have had a repeating problem with DELL optiplex hardware. It appears the IO connected to the NI is able to (via the NI) power the PCI bus on the PC, to the extent that an LED is lit on the motherboard when the NI lead is plugged in but the PC is powererd off. This stops the PC from powering up at all normally. The only fix is to power up the PC then the connected hardware, the interface is a simple 5v TTL line level stuff and has not changed. The PC and hardware are remotely located so powering up in order is painful.

Can you suggest a fix , has anyone else reported this effect ?

Regards,

Chris Hogg

[K_Bull]

Hi Chris,
Can I ask what hardware you are connecting to the PCI 6534 using what cable?
When the computer is first turned on, all lines are configured for input. Each data line and control line has an internal resistor that can pull up (connect the line to +5VDC) or pull down (connect the line to ground). By default, the data and control lines are pulled down. To make the internal resistors pull up, connect the CPULL line (for the control lines) or the DPULL line (for the data lines) to the +5VDC pin.
Is this issue reproducible if you plug the card into another computer with different spec (if possible)?
Look forward to hearing from you.
Regards,

[ChrisHogg]

Hi Kabul, thanks for the reply.

We are connecting a piece of proprietary kit via an NI 68pin - 68pin lead to the NI-6534. The device has worked fine for several years with previous DELL models but since the move to PCIe Optiplex 745 motherboards we have seen this booting problem, it has been repeated on all the machines of this type we have tried. As this effects the PC powering on, the NI is not configured yet so I assume it is input mode. Our board is sending out data on 3 of the four IO groups continually and uses the fourth group for control.

We have jumpers for CPULL and DPULL on the board, at the moment they are set to pull up, we can try swapping it to pull down and see if it makes any difference to the problem.

At the moment we have to boot the PC then switch our board on, then the system will operate normally.

I will post the results of the CPULL, DPULL tests once we try them.

Cheers, Chris