Computer Automated Measurement and Control

Computer Automated Measurement And Control ( CAMAC ) is a bus system for data acquisition and experiment control in nuclear and particle physics. The bus allows data exchange between plug-in (up to 24 in a superframe, Crate called ) and a so-called Crate controller, which then connects to a PC or a VME - CAMAC interface.

The standard also defines the mechanical, electrical, and logical attributes of the parallel bus to the plug. More systems standards have been defined to consist of several frames. Among them, the "parallel branch highway " and the " Serial Highway". Manufacturer-specific interfaces were also built.

The CAMAC standard includes the following IEEE standards:

• 583 The basic standard
• 683 specifications for the block transfer (Q -stop and Q- scan)
• 596 Parallel Branch Highway system
• 595 Serial highway system
• 726 Real-time Basic for CAMAC
• 675 Auxiliary crate controller specification / support
• 758 FORTRAN subroutines for CAMAC.

Within the superframe, the plug-in cards are by their position identified (geographical addressing). The numbering starts at the left. The last two places are provided for the control interface. Within a module, the standard defines 16 sub-addresses (0-15). Commands to the module are specified over 32 (0-31 ) short codes. Here are the codes 0-7 for read operations and 16 are provided to 23 for write operations.

In addition, the following global functions are still defined:

• I - Crate inhibit ( = block, block )
• Z - Crate zero. ( = Reset )
• C - Crate clear. ( Delete = module content )

The original standard was to be able to transmit 24 bits of data per microsecond. Later revisions to support so-called " short cycles " with a transfer time of 450ns. Further improvements seen it before, adjust the cycle time individually to the individual modules.