SignalExpress and the usb-6259

[Greenies]

We are trying to use SignalExpress and the USB-6259 to generate digital outputs without success. Do all the digital I/O lines on this module require an external sample clock to work correctly. Any information would be appreciated

[Greenies]

We are trying to use SignalExpress and the USB-6259 to generate digital outputs without success. Do all the digital I/O lines on this module require an external sample clock to work correctly. Any information would be appreciated

[S.Limb]

Hello Greenies

Thank you for your posts, as I have said on your other message, I hope it is ok for me to contact you on just the one page as it saves repeating ourselves. I would also like to mention that in future it is better to post on one board so that other users can search discussions with more ease.

As I understand you have queries regarding the digital I/O of the USB 6259, I firstly recommend looking in the manual for your device to see if this is already documented.

"Each DIO and PFI signal is protected against overvoltage, undervoltage, and overcurrent conditions as well as ESD events. However, you should avoid these fault conditions by following these guidelines:

• If you configure a PFI or DIO line as an output, do not connect it to any external signal source, ground, or power supply.
• If you configure a PFI or DIO line as an output, understand the current requirements of the load connected to these signals. Do not exceed the specified current output limits of the DAQ device. NI has several signal conditioning solutions for digital applications requiring high current drive.
• If you configure a PFI or DIO line as an input, do not drive the line with voltages outside of its normal operating range. The PFI or DIO lines have a smaller operating range than the AI signals.
• Treat the DAQ device as you would treat any static sensitive device. Always properly ground yourself and the equipment when handling the DAQ device or connecting to it."

This information was taken from chapter 6 of the manual, there is also information about connecting signals for DIO on page 10 of chapter 6.

Specifications

Manual

Here are some articles which discuss DIO functionality, these may also help you with your development.

DIO benchmarks

DIO

Please let me know if your questions are answered in these documents, if you still have outstanding queries, please reply so I can continue to offer you support.

Regards

[Greenies]

Hi

Our main problem is using SignalExpress to generate a waveform (such as a clock signal) on a digital output from the board. Do you need an external sample clock connected to the board for this to happen? (PFI input) There also seems no option on Signal Express to define what is a digital input or output for this board

Thanks Brian

[S.Limb]

Hi Brian

I can now see why you were having issues getting this setup. I have attached an example for you to look at, if you are not using LabVIEW 2010 please let me know as I can create another version for you.

To send a waveform to a digital output these are the steps.

Create a digital waveform

Create a generation task for DIO

In the step view click on the arrow at the bottom right of the DAQ step, theis will give you the option to choose a waveform.

I hope this answers your question, please get in touch to let me know how you get on or if you have any further queries.

Regards

[Greenies]

Hi Stephanie

If I try your project on our setup I get an error message requiring   that an external sample clock needs to be specified

Best Regards

Brian

[S.Limb]

Hello Brian

I hope your weekend went well.

It does seem strange that you get this error as I have been unable to reproduce the error you see when running the code. I expect that the error may be due to a change in hardware, if you follow these steps and then run the code are you able to perform the task?

- Open the DAQmx generate step

- Right click the device name and select change physical channel

- Expand the tree and select the line on your PCI 6259

- In my example I have selected N samples for the generation mode, 100 samples to write and 100Hz, these can be altered according to your application and setup

- In the advanced timing tab these are the current settings, you may want to change these to be configured with your system as well.

If you are still having troubles please let me know and I will find an alternative example.

This is an example I found on the web, which may help you with understanding signal express, and setting up steps.

I hope that we can get your system up and running shortly.

Regards

[Greenies]

Hello Stephanie

Still no luck. I think this set up requires an external sample clock to work on input PFI0. We still get error messages implying that the sample clock is missing. Is there no way to get the digital inputs/outputs working with an internal sample clock on the module?

Thanks

Brian

[S.Limb]

Hello Brian

Unfortunately it is not possible for the 6259 to divide the timebase and produce a clock signal, the only alternative is to use an external source, wiring a clock signal to one of the PFI lines. This is documented in the manual page 6-4.

Let me know if you would like any further assistance with implementing this.

Regards