The IEC625.1 standard used a 25 pole DSUB connector for the bus, the IEEE488.1 standard favored a Centronics-like 24 pole connector. Today, the 24 pole connector is always used, but there are also adaptors available in case older instruments are equipped with a 25 pole DSUB connector. For these historical reasons, there exist several names for the same thing. Bus properties Up to 15 instruments, called devices , can be connected to one computer, usually called controller , because it is responsible for coordinating bus traffic. EN able disables the device's front-panel operation.
Device is controlled by controller .
I dentify is basically used as termination indicator in data transfers. ATN - AT tentio N , is a means of the controller to distinguish between data transfer and control messages. Same command names result in similar actions. In contrast to the '.1' standard that defines physical means like cables, timing and so on, the '.2' standard focuses on the instrument model. It is currently adopted.