Mechatronics, Industrial Control & Instrumentation

CAMAC (IEEE-583) Modular Instrumentation Standard

The IEEE-583, IEEE-595, and IEEE 596 CAMAC (Computer Aided Measurement and Control) standards define a hardware and data transmission system which is used to house, support and communicate with various compatible instrumentation modules.

A typical CAMAC crate shown in Figure 1.0 below is a physical package which has 25 slots or powered stations for compatible, plug-in instruments. In general, the two right hand slots are used to house the CAMAC controller module. The controller module allows the individual modules to be coordinated and controlled by an external computer using the IEEE-488.2 bus or in some instances an RS-232C interface.

Figure 1.0: A partially filled CAMAC crate, source: LeCroy corp, presently called Teledyne LeCroy

The commands and data transfers to and from the modules and the controller are made via the CAMAC DATAWAY, which use 24-bit data words. Figure 1.1 below illustrates the (internal) DATAWAY connections to three modules in a CAMAC system. The read and write lines are each 24 bits wide. Two lines are used for the timing strobes; there are three common control lines, three status lines, four address bus lines, five function lines, and one station number line per module, for a total of 66 lines per module.

Figure 1.1 DATAWAY signal paths to three CAMAC modules from a crate controller, source: LeCroy corp, presently called Teledyne LeCroy

The key advantage of CAMAC housed instrumentation is its ease of use through GPIB and its speed in local data manipulation. Individual instrument modules are managed by the CAMAC controller over the DATAWAY and only one GPIB bus is needed. CAMAC systems represent top-of-the-line instrumentation, and are expensive per se. They are widely used in large industrial applications and for measurements in particle detectors for nuclear & particle physics and in plasma physics.

Related articles:

John Mulindi

John Mulindi is an Industrial Instrumentation and Control Professional with a wide range of experience in electrical and electronics, process measurement, control systems and automation. In free time he spends time reading, taking adventure walks and watching football.