Agilent Technologies E1437A User Manual page 95

20 msample/second adc with filters and fifo

Table of Contents

E1437A User's Guide

VXI plug&play Programming Reference

In addition to controlling the progression through the four module states, the SYNC

signal is used to allow for synchronizing the decimation counters and local oscillators

of multiple E1437 modules. This is done by calling hpe1437_filter_sync and/or

hpe1437_frequency_sync prior to asserting SYNC with hpe1437_meas_control. This

is normally done with the module in the Idle state; however, the center frequency can

also be changed in the Measure state with hpe1437_frequency_sync if the modules

are all programmed for continuous (non-block mode) data collection.

If all modules in a multi-module system are in the Idle state when the

hpe1437_meas_control sync parameter is asserted, the LO frequency will be updated

and the next measurement will be armed. If all modules are in the measurement state in

continuous mode, the LO frequency will be synchronously updated, and the

measurement will continue. In continuous mode you should ensure that all modules are

in the same state, either the Idle state or the Measure state, before using

hpe1437_meas_control to assert SYNC. Otherwise some modules will re-arm while

others will continue the current measurement. In block mode the sync assertion will be

ignored unless all modules are in the Idle state.

The hpe1437_meas_control function assures that a single module is in a valid state by

checking that the hardware complete and sync valid bits in the status register are both

true. In synchronous multi-module systems you should use the hpe1437_wait function

for each module to assure a valid state in non-master modules within a synchronous

group.

In the case of systems made up of multiple mainframes you must be aware that only

modules in mainframe A may assert sync. Any sync asserted in other mainframes is

ignored.

Example

The program multichan.exe described in Example Programs provides an example of

how to correctly set up a multi-module measurement using hpe1437_meas_control to

initiate state transitions.

Reset Values

idle

sync

Effect on Active

This command may or may not abort any measurement in progress when any

Measurement

parameter value is changed, depending on the write value.