CAMAC standard

Maybe the most important advantage of the CAMAC standard is the fact that a large number of modules with different functions are commercially available as a spin-off of high energy physics developments. As a result a substantial amount of designing and building time can be saved because only some adaptions in the standardized CAMAC software have to be made. 

Control of the separator will be by a microprocessor based serial CAMAC system using standard CERN interfaces, and work is progressing rapidly in this domain. A control room, close to the SC control room, is being prepared, much of the CAMAC hardware is available already, and a start has been made on the software. 

CAMAC Instrumentation and Interface Standards, IEEE Publication, Wiley Interscience (1976)... 

There are minicomputers on the market which were developed for pulse/FT NMR use and contain a complete interface and have a library of programs appropriate for NMR data manipulation. An alternative is to purchase a CAMAC crate as an interface to a standard minicomputer and then... 

In this spectrometer, the timing and the digitizing functions already mentioned, as well as several other functions are performed by modules located in a CAMAC crate. A discussion of CAMAC will follow in the next section (V.C.3.). Simply described, it is a commercially standardized hardware system interfaced to the minicomputer with a few hundred modules of all kinds available commercially. 

The hardware cost associated with CAMAC also represents a middle ground between a homebuilt interface and a commercially built interface. The software must still be written for the particular system as in the case of a homebuilt interface but, due to the standardization of the commands required for the modules, the task is a little easier with the CAMAC interface. Furthermore, since CAMAC modules are commercially available, any programs written for a CAMAC system can be adapted quite easily for another CAMAC system. 

CAMAC is an international standard for modular computer instrumentation. It specifies the electrical, mechanical, and functional characteristics of modular instruments to be plugged into a standard multi-receptacle "crate" which, in turn, can be interfaced to a minicomputer. The unique feature of CAMAC systems, as opposed to other modular systems, is that the modules not only get power from the crate but the "data-way" between the modules and the crate "controller" can carry 24-bits of data in each direction in addition to various function, address, and flag signals. The controller resides in the crate as a module and acts as an interface between the modules and a specific computer. Some of the lines in the dataway are location-specific so that a module in a given slot can be addressed by the controller. The modules (except for the controller) cannot communicate with other modules except through the controller. 

A wide variety of counting systems has been developed for various purposes. Equipment is often built as NIM (Nuclear Instrument Module standard) or CAMAC (Computer Automated Measurement And Control standard) modules, which fit into standard bins (or crates) containing power supplies and some inter-module connections. Cable connectors are also largely standardized. This facilitates combinations of bias supplies, amplifiers, discriminators, SCAs, ADCs, counters, and other circuitry to fit any need as well as their connection to computers. Some non-standard units, e.g. portable instruments, have their own power supply, main amplifier, counter or rate-meter, etc. 

The CMU medium energy physics group is in the process of switching from a CAMAC-based data acquisition system to the more powerful FASTBUS standard. The advantages are numerous higher densities for more cost effective modules (typically, FASTBUS modules cost l/4 li their CAMAC counterparts), suppression of invalid data for more efficient data collection, smart crate controllers for better local control of data acquisition, faster read-out, and more. 

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