How to send data via USB to a HID device

[florindaniel]

Hello,

I need to send data to a HID customer display connected via USB.

Any idea on how to do it? I've found no specs on the DLL and functions to do that.

Thank you,
Daniel

 

[GriffMG]

I think we would need a little more info, does your HID come with any documentation, a support CD or whatever?

Are you trying to communicate with it from a VFP app?

I have a USB experiment board that came with a dll and some basic documentation
on how to 'talk' to it.

Regards

Griff
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[florindaniel]

- yes, there's a VFP application sending that data
- the device has no drivers but it complies with HID specs
- ASCII strings are to be sent to the device

thank you

 

[Olaf Doschke]

I never did USB low level, no idea. I fear it does not compare to COM to FOPEN and FWRITE to it.
Is it a scale? Then the usual thing detected is a virtual COM Port, and then you are at normal COM Port communication.

It would really be helpful to know the device, as I don't think there is a general standard communication with USB, eg see

http://www.howtogeek.com/208611/is-there-an-actual-usb-communication-protocol/

Bye, Olaf.

PS: forget the question about the scale, a HID is a human interface device. But it might still apply to some devices classically having a COM interface, eg simpler displays with LEDs, not a LED screen, but the single red LEDs for example.

Is there any manual?

Bye, Olaf.

 

[GriffMG]

Not my area of expertise, but try here:

http://www.kadtronix.com/usbhidapi_usr.htm

Regards

Griff
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There are 10 kinds of people in the world, those who understand binary and those who don't.

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[Mike Lewis]

Not my area either, but I think you'd almost certainly need the specs for the specific device. USB/HID can cover anything form a keyboard to advanced telemetry instruments, so a generic USB/HID spec isn't going to help you.

Can you tell us exactly what this "customer display" is? Also, even if you don't have any technical docs for it, are there any instructions for using it with a standard Windows PC? For example, can you configure it via Control Panel?

Mike

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[florindaniel]

Sorry for the lack of information but I really belive are of no interest for the idea.
HID is standardised and there seemd to be a Hid.Dll havin some Write and Read methods and THESE are the methods I am interested in (actually your experience with that).
A customer diaplay shows some messaes and you cand send to it somethin like Chr(27)+Chr(J)+"Hello Joe" but for other devices the strin can differ, that's why I say it is not important what the data is.

So, basically, the idea is the one stated in the beginning: how to send a string to a HID device via USB? It doesn't matter the content of the string and not even what kind of device is on the other end.

It seems there's some good info on Griff's link, thank you.

 

[Olaf Doschke]

Of course it's not important what the string is you want to send, that's unimportant in any API description, be it general for any HID or a specific device.
If you have a device without any manual that sounds like the type of low level electronic module you could buy in a hardware electronics store and have to know the low level specifics.
Indeed there are some low level Open(), Read() and Write() methods, but even with a component for hardware developers and not end users, such as a display, I would expect you to be able to find some manual to it.
There has to be some USB controller chip and at least that would have a manual you could get from the vendor.

Bye, Olaf.