Can't the number of report_id be more than 5?

[12345678]

I am making HID composite devices, but I find that if the number of report ids is more than 5, I cannot send data from PC to this device；Error code 1784 is displayed

If less than 5, the data can be sent successfully

[12345678]

Hello, I have configured my device separately as a custom device (for data transfer) capable of sending data.

But when configured with a keyboard and a custom device (for data transfer), the PC cannot send data and will fail to open the device

[Sigurd]

Error code 1784 is displayed

What function is returning this error-code ?

12345678 said:

But when configured with a keyboard and a custom device (for data transfer), the PC cannot send data and will fail to open the device

Make sure that you use a different endpoint for the keyboard and the data-transfer. It might be helpful to take a look at the usbd_hid_composite example.