USB-6009 Digital Power up state

[zener]

Hi,

I have a USB 6009.  I need the digital ports to be 0V when the unit powers up.  I have a 10K to ground on all the ports but they still power up at 2.5 V.  Once I reset them with the software they are fine.  Is there a setting in Max somewhere for this?

Thanks

[J_Thomas]

Hi zener,

Unfortunately, the USB-6009 has very limited options for configuring it to power-up with logic low.

The USB-6008/6009 has an internal pull-up resistor that has a 4.7 kOhm resistance. This causes the digital outputs on the device to have a logic high start-up state. Attaching a pull-down resistor is not the answer to achieve a logic low start up state on the USB-6008/6009. A pull-down resistor can be used with 653x series of DIO cards, but it is not recommended for the USB-6008/6009. Since the 600x board already have an internal pull-up resistor, attaching a pull down resistor to the USB-6008/6009 will essentially create a voltage divider and will cause the device to not work properly.

This is best explained in the following document:

Can I Use a Pull-down Resistor on My USB-6008/6009 Digital Outputs to Obtain a Logic Low Start-up St...
Your basic options are to put an inverter on the lines that you need to start low or look into another board that does support programmable power up states.

Hope this helps.

[zener]

Thanks, I was afraid of that.

[dave_vic_ozz1]

Old thread drag up here. It gets a few views.

We love these devices but the start up is an issue. The best work around we found was

- DO_0 controls a relay. NC contacts power all other control circuits.

- USB-6009 Output is on by default so when 6009 is uncontrolled a relay triggered from DO_0 operates .

- We command the DO_0 output to OFF in code after LabView runs.

- The DO_0 goes low de-energising a relay, closing the NC contacts. These NC contacts then power our control and 'safe' circuits.