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Datasheets and User Guides

App Notes

Software & Driver

 

2.1 - USB

For information about USB installation, see Section 1.

The U3 has a full-speed USB connection compatible with USB version 1.1 or 2.0. This connection provides communication and power (Vusb). USB ground is connected to the U3 ground (GND), and USB ground is generally the same as the ground of the PC chassis and AC mains.

The details of the U3 USB interface are handled by the high level drivers (Windows LabJackUD DLL), so the following information is really only needed when developing low-level drivers.

The LabJack vendor ID is 0x0CD5. The product ID for the U3 is 0x0003.

The USB interface consists of the normal bidirectional control endpoint (0 OUT & IN), 3 used bulk endpoints (1 OUT, 2 IN, 3 IN), and 1 dummy endpoint (3 OUT). Endpoint 1 consists of a 64 byte OUT endpoint (address = 0x01). Endpoint 2 consists of a 64 byte IN endpoint (address = 0x82). Endpoint 3 consists of a dummy OUT endpoint (address = 0x03) and a 64 byte IN endpoint (address = 0x83). Endpoint 3 OUT is not supported by the firmware, and should never be used.

All commands should always be sent on Endpoint 1, and the responses to commands will always be on Endpoint 2. Endpoint 3 is only used to send stream data from the U3 to the host.