Agilent Technologies E1439 manual Measurement loop in multi-module systems

Using the Agilent E1439

The measurement loop

Modules programmed for block mode operation assert the Sync line until a complete block of data, including any pre-programmed pre- or post-trigger delay, has been collected and is available to the I/O port. The module then releases the Sync line. The module returns to the Idle state when the block of data has been collected.

In continuous mode, a module releases sync immediately but moves to the Idle state only if explicitly programmed to do so or if the FIFO data buffer overflows because data cannot be read from the I/O port fast enough.

The measurement loop in multi-module systems

The following rules generally apply to transitions between states when multiple modules share a Sync signal:

•If any one module asserts the Sync line, a synchronous state transition occurs for all modules in a system.

•All modules in a system must have released the Sync line in order to bring about a synchronous transition to Trigger state.

•In block mode, each module releases the Sync line after its block of data has been collected. Immediately upon entering the Measure state in continuous mode, each module releases the Sync line. It continues to collect and output data until it is programatically signaled to stop or until the FIFO overflows. With the Sync line released it is then possible to change the center frequency for one or multiple modules without interrupting the measurement. See “Synchronizing changes in multi-module systems” on page 39.

•A module may be programmed explicitly to inhibit its transition to the Arm state despite Sync transitions.

•In addition to controlling the progression through the four module states, the Sync signal is used to synchronize the decimation counters and local oscillators of multiple E1439 modules.

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