DAQ-6501 reset on windows power up.

[linu95k]

Hi,

Is there a way to automatically reset my NI-USB-6501 Digital DAQ on windows power up and shutdown?

I have a System which uses DAQ digital output connected to a buzzer. The problem I am facing is that when the windows is booted or shutdown the DAQ power cycles causing all the Digital output points to be ON which rings the buzzer until the operator runs the application which resets the DAQ lines.

Is there a way to Reset the DAQ on startup or shutdown of windows?

Or prevent it from powering on until required?

[GerdW]

Hi linu,

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@linu95k wrote:

Is there a way to Reset the DAQ on startup or shutdown of windows?

Or prevent it from powering on until required?

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Did you read the specs?

It says: "power on state = Input" for all DIOs!

So your USB6501 doesn't output "ON" on it's DOs, but switches them to (high-resistance) input pins! And there's no way to prevent this in the case of a power cycle...

What about some external hardware where you need to switch an (additional) DO pin to a predefined state to enable all other outputs and so prevent the buzzer (and all other connected devices) from also turning on?

[santo_13]

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@linu95k wrote:

Hi,

Is there a way to automatically reset my NI-USB-6501 Digital DAQ on windows power up and shutdown?

I have a System which uses DAQ digital output connected to a buzzer. The problem I am facing is that when the windows is booted or shutdown the DAQ power cycles causing all the Digital output points to be ON which rings the buzzer until the operator runs the application which resets the DAQ lines.

Is there a way to Reset the DAQ on startup or shutdown of windows?

Or prevent it from powering on until required?

---

Unfortunately, No. You need a more advanced DAQ card to be able to configure the power-up state. If the equipment connected on the other end of the 6501 is critical, then you should not be restarting your computer at all. Consider 6501 as a part of your computer, if your computer turns off, your 6501 also turns off.

[rolfk]

Basically your external logic is flawed. To prevent potential shortcircuits with external hardware trying to drive those ports as an input the only save power up state for all of those pins is to configure them as high impedance inputs. Usually there is some very high impedance pull up or pull down resistance internal at the pin to prevent the pin from floating which could cause the receiver to constantly see it flipper around the threshold and eventually even overload the internal transistors and damage them.

If you want a specific level on that pin you have to design your hardware accordingly. An option might be to simply put an external pull down resistor on that pin but you need to read the specs of the device as to what the maximum current is that it can drive to ground and subtract the input current for your external circuit from it. I would start with a 47k resistor and measure the voltage at the pin in powered up but uninitialized state an then again when the signal is set active from your software. The voltage in powered up but uninitialized state should be below 0.8V but trying to keep it below half of that is better. In enabled state the voltage should be above 3.5V but higher is better.

Another option is to invert the logic of you external circuit by making the naturally visible high impedance state created by the internal pull up or pull down your inactive state and drive the circuit with the opposite level.

If you want to visit a place and that place doesn’t come to you you have to go there. 🙂

[JÞB]

Use an external hub that has a power supply independent of the Windows machine!  Obviously,  when Windows reboots the internal supply shuts off.  You don't want to power cycle the device.