Two functions that are still being defined under the standard are graphics and moving maps. According to Marlin Melander, marketing manager for Raven Industries, a VT is divided into four quadrants to show a lot of information at the same time. “Some of those windows are going to be fairly small,” Melander says. “So while VTs work fine for showing digital or numeric information such as rates being applied, most VTs do not have processors or graphics accelerators to be able to show maps.”

George Huber, global sales manager with Trimble Agricultural Division, says another limitation of the ISO 11783 protocol is message latency. “Some messages, such as GPS, are highly time critical,” he says. The standard does not ensure that the GPS signal is placed in the front of the messaging stream.