Is USB-DIO24 slower than PCI-DIO24?

[Nim]

Hello,

I run a python program that generate the SPI signals on the digital input/output ports on PCI-DIO24 and USB-DIO24. The problem is on the PCI-DIO24 the SPI clock frequency is 20KHZ but in the USB-DIO24 it is about 20 HZ while the Python codes on both devices are identical.

Please guide me in this matter.

[Fausto]

Hello @Nim.

Please provide additional information regarding your application, python code, and software configuration.  Are you using UL Python for Windows or third-party drivers for Linux?

Regards,

Fausto

[Nim]

Hello Fausto,

I am using UL python for windows.

Also, I attached the signal that captured from SPI bus by Logic Analyzer.

 

Thank you,

[Nim]

Also, it good to be mentioned, on the PCI version, I started with UL in C and did a Python wrapper, so I am actually using the C version of the UL.

[Fausto]

Hello @Nim.

The following MCC knowledgebase article may shed some light between the PCI and USB bus times.

https://kb.mccdaq.com/KnowledgebaseArticle50176.aspx

 

[Nim]

Fausto,

Thank you for the link. 

In the following link Attila said, The DIOs should also handle 20MHz SPI

 

[Fausto]

@Nim,

MCC products like the PCI-DIO24 and USB-DIO24 do not support SPI protocols.  That forum post relates to Digilent products.

Regards,

Fausto

[ryan_mlc]

@Fausto

Nim is no longer working on this project so I may follow up with more information or questions in the future.

 

But what we are doing is bit-banging SPI protocol on Port C of the DIO24. This has not been an issue with the PCI version but it's much slow after we have switched to the USB version.

 

Thanks,

Ryan

Edited October 11, 2022 by ryan_mlc
Tagging a person

[craig.benson]

I also have a USB-DIO24 board and a PCI-DIO24 board that I am pulsing stepper motors with and the USB-DIO24 appears to be significantly slower.  While I understand there may be some software related dependency, it seems like the write times are significantly slower.

[ryan_mlc]

On 10/12/2022 at 1:50 PM, craig.benson said:

I also have a USB-DIO24 board and a PCI-DIO24 board that I am pulsing stepper motors with and the USB-DIO24 appears to be significantly slower.  While I understand there may be some software related dependency, it seems like the write times are significantly slower.

Glad we are not the only ones having this issue. Hopefully we can get a response from MCC Staff about this.

@Faustoany input about this?

[ryan_mlc]

On 10/12/2022 at 1:50 PM, craig.benson said:

I also have a USB-DIO24 board and a PCI-DIO24 board that I am pulsing stepper motors with and the USB-DIO24 appears to be significantly slower.  While I understand there may be some software related dependency, it seems like the write times are significantly slower.

Have you been to figure out if there is a way to speed it up?

[Fausto]

Hello @ryan_mlc.

There is no clock on the PCI-DIO24 board nor on the USB-DIO24 Series.  The rates are system dependent and the USB bus is significantly slower that the PCI bus.  There is no way to speed it up.

If your application requires faster rates, consider Digilent's Analog Discovery 2.

https://digilent.com/shop/analog-discovery-2-100ms-s-usb-oscilloscope-logic-analyzer-and-variable-power-supply/

Regards,

Fausto

[ryan_mlc]

45 minutes ago, Fausto said:

Hello @ryan_mlc.

There is no clock on the PCI-DIO24 board nor on the USB-DIO24 Series.  The rates are system dependent and the USB bus is significantly slower that the PCI bus.  There is no way to speed it up.

If your application requires faster rates, consider Digilent's Analog Discovery 2.

https://digilent.com/shop/analog-discovery-2-100ms-s-usb-oscilloscope-logic-analyzer-and-variable-power-supply/

Regards,

Fausto

Thanks for the info. We should probably try a faster computer than we are currently on.

 

Also, do you have a product that is more focused on just GPIO controls? That device seems to have functions well beyond our needs and is short of the 24 DIO ports needed in our current project.

 

Regards,

Ryan

[Fausto]

@Ryan,

Take a look at Digilent's Digital Discovery module.

https://digilent.com/shop/digital-discovery-portable-usb-logic-analyzer-and-digital-pattern-generator/

Regards,

Fausto