IEEE 488-1978 pdf free.IEEE Standard Digital Interface for Programmable Instrumentation.
1.1 Scope.This standard applies to interfacesystems used to interconnect both program-mable and nonprogrammable electronic mea-suring apparatus withother apparatus andaccessories necessary to assemble instrumen-tation systems.
It applies to the interface of instrumenta-tion systems,or portions of them，in whichthe:
(1) Dataexchanged among the intercon-nected apparatus is digital (as distinct fromanalog)
( 2) Number of devices that may be inter-connected by one contiguous bus does not ex-ceed 15
(3) Total transmission path lengths over theinterconnecting cables does not exceed 20 m(4) Data rate across the interface on anysignal line does not exceed 1 Mb/s.The basic functional specifications of this standard may be used in digital interfaceapplications which require longer distances,
more devices,increased noise immunity, or combinations of these.Different electricaland mechanicalspecifications may be required (for example,symmetrical circuit configurations，high threshold logic，special connectors,or cable configurations) for these extended applications.This standard may also be applicable toother instrumentation system elements such as
processors，stimulus，display, or storage de-vices,and terminal units found useful in in-strumentation systems.
It applies generally to laboratory and pro-duction test environments whichare bothelectrically quiet and restricted as to physicaldimensions (distances between the systemcomponents).
This standard deals only with the interfacecharacteristics of instrumentation systems tothe exclusion of design specifications,con-sideration of radio-interface regulations，per-formance requirements,and safety require-ments of apparatus.
NOTE: For the latter two items,reference is made toIEC-Publ 348 (1971),Safety Requirements for Elec-tronic Measuring Apparatus,and IEC-Publ 359 (1971),Expression of theFunctional Performance of Elec-tronic Measuring Equipment.1
Throughout this standard, and insofar as fur-ther distinction is not necessary，the term“system”denotes the byte-serial bit-parallelinterface system that,in general，includes allcircuits， cables，connectors，message repertoire,and control protocol to effect un-ambiguous data transfer between devices; andthe term “device”or “apparatus denotes anyprogrammable measurement device or otherproduct connected to the interface systemthat communicates information via，and con-forms to, the interface system definition.
A primary focus of this standard is to setforth an interface system to interconnect self-contained apparatus to other apparatus by external means. This same standard may beapplied to interconnecting the internal sub-sections within a self-contained equipment.IEEE 488 pdf download.