The Ieee Signal Lines; The Data Bus Signals; The Handshake Signals; Intro - Brainboxes PS-307 User Manual

PSI BOX Reference
resistor once the voltage has stabilised. In this way IEEE
instruments can be easily built up to form a simple but effective
automatic test system.
So the IEEE Standard 488 specifies a digital interface for
programmable instrumentation, that is, it is a way of inter-
connecting electronic measuring and control apparatus.
____________________ _

The IEEE Signal Lines.

The IEEE 488 defines the use of a parallel bus to
interconnect up to 15 instruments. Each device on the bus is
connected to the 16 signal lines and 8 ground lines on the bus.
These 16 signal lines can be considered as three separate groups.
Eight of the lines are used to carry data and commands. Three
lines control the transfer of the data. Whilst the remaining five
lines are for general interface management.
These three groups are the 8 Data Bus signals, the 3 Handshake
signals and the 5 Management signals.
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The Data Bus Signals.

The 8 data bus signals are called DIO1 to DIO8.
The data bus carries all data, programming instructions and IEEE
interface messages. Most instruments communicate using the 7
bit ASCII code, however the information on the data bus may
represent ASCII, Binary, Hex, Octal, or whatever, characters.
____________________ _

The Handshake Signals.

The 3 handshake signals are DAV, NRFD and NDAC.
The handshake signals control the actual transfer of each data
byte down the data bus. They provide the famous '3-wire
handshake' that ensures that the data is transmitted correctly and
without loss, no matter what the difference in operating speeds
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____________________ _ The IEEE Signal Lines.
IEEE 488 Introduction
Chapter 2