The Measurement Loop In Multi-Module Systems - Agilent Technologies E1437A User Manual

E1437A User's Guide
Using the E1437A
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:
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If any one module asserts the SYNC line a synchronous state transition occurs
for all modules in a system.
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All modules in a system must have released the SYNC line in order to bring
about a synchronous transition to Trigger state.
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In block mode each module releases the SYNC line after its block of data has
been collected. After each block mode module has released the SYNC line the
individual module moves to the Idle state.
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Immediately upon entering the Measure state in continuous mode each module
releases the SYNC line but does not move into the Idle state. 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 the section on Synchronizing Changes in Multi-Module
Systems.
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A module may be programmed explicitly to inhibit its transition to the Arm state
despite SYNC transitions.
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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 E1437 modules.
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