CAMAC
Computer Automated Measurement And Control ( CAMAC ) is a data transmission system, a bus system for data acquisition and experiment control in nuclear and particle physics . The bus allows data to be exchanged between plug-in cards (up to 24 in a superframe, called a crate) and a so-called crate controller, which then establishes a connection to a PC or a VME- CAMAC interface.
The standard defines the mechanical, electrical and logical properties of the parallel bus for the plug-in cards. Several standards have been defined for systems that consist of several superframes. These include 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 block transfer (Q-stop and Q-scan)
- 596 Parallel Branch Highway systems
- 595 Serial highway system
- 726 Realtime Basic for CAMAC
- 675 Auxiliary crate controller specification / support
- 758 FORTRAN routines for CAMAC.
The plug-in cards are identified by their location within the frame (geographical addressing). The numbering starts on the left. The last two places are intended for the control interface. The standard defines 16 sub-addresses (0–15) within a module. Commands to the module are specified using 32 (0–31) function codes. The codes 0 to 7 are provided for read operations and 16 to 23 for write operations.
In addition, the following global functions are defined:
- I - Crate inhibit (= block, block)
- Z - Crate zero. (= reset)
- C - Crate clear. (= Delete module content)
The original standard was able to transmit 24 bits of data per microsecond. Later revisions support so-called “short cycles” with a transfer time of 450 ns . Further improvements provide for the cycle time to be individually adapted to the individual modules.
See also
- Data acquisition
- VMEbus
- NIM
- LEMO connector