What is the difference between ISOBUS VT Version 3 and Version 4?

VIRTEC display.

The ISO 11783-6 standard was most recently released in 2010. As of this release, three common versions of the Virtual Terminal (VT) are specified. These versions are referenced in the standard as “Version 2”, “Version 3”, and “Version 4”. Based on recent ISOBUS Plugfest attendance, a survey of the industry shows a few Version 2 devices still in common use, a small number of Version 4 devices in use, and a large majority of devices using Version 3. The standard requires that an Electronic Control Unit (ECU) and a VT communicating via the VT standard should use the standard according to the lowest VT version of the pair, e.g. a VT at Version 4 and an ECU at Version 3 should use Version 3 communications.