USBTMC

USBTMC, or USB Test and Measurement Class, is a USB device class defined by the USB Implementers Forum (USB-IF) to enable communication with laboratory instruments over USB using a standard protocol. The class is designed for testers and measurement equipment such as oscilloscopes, multimeters, spectrum analyzers, signal generators, power supplies, and data loggers, allowing software to interact with a wide range of devices without vendor-specific drivers.

The USBTMC specification defines a simple, message-based protocol that runs over the USB bulk transfer endpoints. A USBTMC device presents a control interface and one or more data interfaces, with host software sending command messages and receiving responses and data. Device capabilities describe supported features, including data formats, triggering, and status reporting. The goal is interoperability: software stacks such as NI-VISA, Keysight IO Libraries, LabVIEW, MATLAB, and PyVISA can communicate with USBTMC instruments, sometimes via generic drivers provided by the operating system or by instrument vendors.

USBTMC has optional extensions, including USB488 compatibility that allows USBTMC instruments to be addressed using GPIB-style commands when connected to software expecting a IEEE-488 device. This bridges modern USB instruments with legacy test equipment and software ecosystems.

History and governance: The USB-IF standardized USBTMC to facilitate plug-and-play connectivity and software compatibility in laboratory environments, with revisions to address performance and interoperability. See also GPIB/IEEE 488, VISA, IVI Foundation, USB-IF.