VXIbus--A Modular Standard for Test & Measurement

System Control-Resource Manager

This module is defined to deliver the CLK10 and access the MODID pins of the modules (also CLK100 and SYNC100 on P3-equipped systems). The Resource Manager should be selected to meet the requirements for all selected instrument modules.

The Resource Manager is known as the Slot 0 Controller. It is a common resource system module containing the VMEbus Resource Manager and VMEbus System Controller. Many Slot 0 modules include other functionality for example, data interfaces (e.g. IEEE-488.1) and system intelligence.

The VXIbus specification defines two common implementations for instruments: register-based devices and message-based devices. Typically, register-based devices are simple modules without embedded intelligence to respond to register reads and writes over the backplane. Examples of register--based devices include digital 110 cards and simple ADCs and DACs. Message-based devices follow the VXIbus word serial communication protocol and are typically devices with embedded microprocessors that receive and execute ASCII commands. The most sophisticated instrument modules are usually message-based devices.

A register-based module requires a message-based module to control il if the user wants to program il using a high level ASCII command language such as IEEE-488.2 or SCPI. The manufacturer of the register-based module specifies the required message-based module. This can be combined with an interface or Slot 0 module, or supplied as an additional module. Message-based modules may have the capability of translating for another message-based module. For example, translation of SCPI messages into the "native" IEEE 488-2 language of the message-based module.

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