OBC or ELD Explained An on-board computer, also known as an Electronic Logging Device (ELD) , is a device that truck drivers use to track their hours of service (HOS) and record other important information related to their trips. The use of ELDs is mandatory for commercial truck drivers in the United States, according to the Federal Motor Carrier Safety Administration (FMCSA). An on-board computer typically consists of a device that is mounted in the truck's cab and connected to the engine's electronic control module. The device can be connected via a wired or wireless connection, depending on the model. The ELD monitors the truck's engine data to determine the vehicle's movement, hours of service, and location. The information gathered by the ELD is used to generate detailed reports that provide insight into the truck driver's performance, including HOS, distance traveled, and speed. This information is also used to help trucking companies comply with r