Power-up state of digital outputs

[Brian_Beal]

I have 2 USB-6210 devices that have the digital output lines connected to OPTO22 relays.  The problem is that when the devices power up, they activate the OPTO22 relays.  The relays are looking to be pulled low to be active.  I have tried changing the power up states in MAX, but all of the relays still come on after power-up.  Any ideas on how to keep the relays off after power up?

[AnalogKid2DigitalMan]

Hi Brian:

Does the 6210 support programmable power up states? I don't have experience with that device but I did quickly look at the manual.

I think the outputs are pulled to ground by a 47K resistor internally, this may be what is firing the OPTO22's.

You may want to try a pull up to resistor to 5V or put inverters between the outputs and the OPTO 22's.

[Brian_Beal]

The progammable states are there in MAX, and it accepts them.  To pull up to 5V, would I use something less then a 47K resistor?

[AnalogKid2DigitalMan]

Brian:

Upon further reading in the manual, I did see that the programmable power up states are supported, odd they are not working in MAX

I wish schematics were available, it's hard to tell what the output stage is comprised of. I'd try a pullup to +5 in the range of 1000 to 10Kohms.

I also saw that total output and +5V accessory current draw is limited to 50mA, I doubt that the OPTO's are drawing that much current to cause odd behaviour, but what is the model number of the OPTO's?

[Brian_Beal]

I am using the G4 OPTO22 modules, and they draw 12mA.  I am using the same modules with a USB-6008, which has a limit of 8.5mA, and they work fine.  I will try the pullup resistor.  Thanks.

[Yardov]

Hello Brian,

The reason your relays might be activated is because you are power them up with the internal +5 V. Then, you can notice that this signal goes high about 1.65 s before the power up states get processed.
So, MAX power up states should be working and if this is not the case you should return your card since it might be damage.
If you can measure the signals with a DMM (or scope) you can see this behavior and you can post back in case you have more questions on this.
Let us know,

[Brian_Beal]

It works now.  I had to stop the Shared Variable Engine to get the power-on state changes to take.

[Yardov]

Hi Brian,

I am glad is working now although I am surprised that the SVE had anything to do with it. During my testing I had mine on all the time.
Thanks for sharing your solution.