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Computer Automated Measurement and Control

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Computer Automated Measurement And Control (CAMAC) is a standard bus for Data acquisition and control used in nuclear and particle physics experiments and in industry. The bus allows data exchange between plug-in modules (up to 24 in a single crate) and a crate controller, which then interfaces to PC or to a VME-CAMAC interface.

The standard was originally defined by the ESONE Committee[1] and covers the mechanical, electrical and logic of a parallel bus (dataway) for the plug-in modules. Several standards have been defined for multiple crate systems including the Parallel Branch Highway definition and Serial Highway definition. Vendor specific Host/Crate interfaces have also been built.

The CAMAC standard encompasses IEEE standards:

Within the dataway, modules are addressed by slot (Geographical addressing). The left most 22 slots are available for application modules while the right most two slots are dedicated to a crate controller. Within a slot the standard defines 16 subaddresses (0-15). A slot commanded by the controller with one of 32 function codes (0-31). Of these function codes, 0-7 are read functions and will transfer data to the controller from the addressed module, while 16-23 are write function codes which will transfer data from the controller to the module.

In addition to functions that address the module, the following global functions are defined:

  • I - Crate inhibit
  • Z - Crate zero.
  • C - Crate clear.

The original standard was capable of one 24 bit data transfer every microsecond. Later a revision to the standard was released to support short cycles which allow a transfer every 450ns. A follow on upwardly compatible standard Fast CAMAC allows the crate cycle time to be tuned to the capabilities of the modules in each slot.

See also

  1. ^ The ESONE committee
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