USB-6009 activates unwanted 5V digital signal when turning on the computer

[PeterHuynh]

Hello!

This may be a known issue, but I couldn't seem to find it in the discussion forums.

As the title describes, upon turning on the computer, the USB-6009 receives power from the USB port and automatically fires 5V from various TTL channels.

This is problematic, as it persistently activates part of our machinery we have attached.

This occurs even when plugging in the USB after the computer is powered up.

The only way to ensure none of the channels are sending 5V outputs is to power up our labview software, and manually send the command to set all TTL channels to 0V.

Is there a way to default all the outputs to 0 upon receiving power?

Thanks,

-Peter

[Dennis_Knutson]

As the manua/specs states, your inexpensive device does not have programmable power up states. They all default to high impedance inputs with a pull-up.

[SnowMule]

6008 is a low-cost device, not a high-performance device.

Build some hardware protection between the DAQ and your equipment to make it fail-safe in the event that the DAQ reinits and pulls all the lines high.  Tristate buffers and inverters help a lot here.

You can also use the analog output to "turn on" the rest of the circuit - that inits at 1V, set a comparator to trigger above 3V and slam that output to 5 when the rest of your outputs are configured.