This standard is applicable to a certain interface system called CAMAC Serial Highway System, designed to be used as a standard interface between a number of CAMAC measuring instruments, display units, control units, actuators, data processing equipment (computers) and communication equipment.
The Serial Highway System is essentially a unidirectional loop used to circulate byte-organized* messages, and to which are connected a System Controller and up to 62 CAMAC crate-assemblies, in accordance with IEC Publication 516: A Modul?r Instrumentation System for Data Handling: CAMAC System, or other controlled devices. The highway transfers data and control information in either bit-serial mode (using one data signal and a bit-clock signal) or byte-serial mode (using eight data signals and a byte-clock signal). Clock r?tes up to 5 MHz may be used, depending on individual system characteristics.
In the primary application, the controlled devices are CAMAC crate assemblies, with Serial Crate Controllers which conform to a defined message structure. In this application the Serial Highway is intended to complement the Parallel Highway defined in IEC Publication 552, CAMAC Organization of Multi-crate Systems. Specification of the Branch Highway and CAMAC Crate Controller Type Al.
This system will be attractive in certain applications that the Parallel Highway was not designed to cover, for example, where there are long distances between crates, or where simplicity of interconnections is desirable. However, the time required to perform a complete operation, including a Dataway cycle, will generally be longer in a serial system than on the Parallel Highway.
The Serial Highway System is defined primarily in terms of the message format and signal standards at the input and output ports of devices connected to the highway. Interconnections between devices may be made directly, using the defined signal standards, or indirectly through Communications channels with other signal standards and types of modulation.
This standard also applies partly to controlled devices connected to the Serial Highway, not necessarily constructed in CAMAC format or controlled by CAMAC commands.
Serial Crate Controllers conforming to the full specification and devices conforming to a certain subset of the full specification can co-exist on the highway without mutual interference.
SIS SS IEC 640:1986 history
1986SIS SS IEC 640:1986 Nuclear instrumentation - CAMAC- Serial highway interface system