Developed by Hewlett-Packard, named Hewlett-Packard Instrument Bus (HP-IB). Later adopted by other manufacturers as GPIB (General Purpose Interface Bus). Become IEEE-488 in 1978.
24 PIN CENTRONICS FEMALE at the Devices.
|1||DIO1||Data Bit 1||Talker|
|2||DIO2||Data Bit 2||Talker|
|3||DIO3||Data Bit 3||Talker|
|4||DIO4||Data Bit 4||Talker|
|5||EOI||End Or Indentity||Talker/Controller|
|7||NRFD||Not Ready For Data||Listener|
|8||NDAC||No Data Accepted||Listener|
|13||DIO5||Data Bit 5||Talker|
|14||DIO6||Data Bit 6||Talker|
|15||DIO7||Data Bit 7||Talker|
|16||DIO8||Data Bit 8||Talker|
- Max 15 devices on one bus
- Max 20 m for all interconnected cables
- Max speed 8000000 B/s
DIO=Data Input Output
Data Valid is a handshake line indicating that the active talker has placed data on the data lines.
NRFD=Not Ready For Data
Not Ready For Data is a handshake line indicating that one or more active listeners is not ready for more data. Note the active talker should then wait before sending any more data on the bus.
NDAC=Not Data Accepted
Not Data Accepted is a handshake line indocating that one or more active listeners has not accepted the current data byte. Note the active talker should leave the current byte asserted on the data lines until it has been accepted ot timed out.
Interface Management Lines
Attention is used primarily to differentiate between command mode and data mode. When ATN is TRUE (I.E. Active high) information on the bus is a command and when ATN is FALSE (Active LOW) the information on the bus is data.
Interface Clear is under the exclusive control of the system controller. When it is active high all devices on the bus are returned to an idle state and the bus is cleared
Remote Enable may be set by the system controller to allow other devices to operate in remote mode.
Service Request can be set by a devive on the interface to indicate it is in need of service. SRQ could be set at the completion of a task. E.g. finished doing a measurement, or when an error as occurred.
EOI=End or Identify
End Or Indentify has two uses. EOI is asserted on the last byte of a data transfer. This signals all devices that no more data should be expected on the transfer.
- IEC 60488-1:2004 (Old standard: IEC 60625-1:1993 / 625-1)
- IEEE 488.1-2003
- ANSI Standard MC 1.1
- Old: IEEE Standard Digital Interface for Programmable Instrumentation, IEEE-488-1978