Model 6517B Electrometer Reference Manual
Appendix D: IEEE-488 bus overview
6517B-901-01 Rev. C / August 2015
D-3
Bus lines
The signal lines on the IEEE-488 bus are grouped into three different categories: Data lines,
management lines, and handshake lines. The data lines handle bus data and commands, while the
management and handshake lines ensure that proper data transfer and operation takes place. Each
bus line is active low, with approximately zero volts representing a logic 1 (true). The following
paragraphs describe the operation of these lines.
Data lines
The IEEE-488 bus uses eight data lines that transfer data one byte at a time. DIO1 (data input/output)
through DIO8 (data input/output) are the eight bidirectional data lines used to transmit both data and
multiline commands. The data lines operate with low true logic.
