can the ipad be connected by usb to another device
Connecting Other USB Devices. Before connecting any USB device to an iPad, it's important to remember that Apple recommends using the camera adapter to connect only cameras. That said, many people have found they can successfully connect USB keyboards, microphones and MIDI audio devices to the camera connector.
To use the Apple USB 3 Camera Adapter, you need an iPhone, iPad, or iPod touch with iOS 9.3 or later. Some USB devices need more power than your iPhone, iPad, or iPod touch can provide. Connect the USB devices to a powered USB hub or secondary power source. Use a Lightning to USB 3 Camera Adapter.