Racal Instruments 3152, User Manual

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Using The Instrument 3-31
Backplane Inter-
Module
Synchronization
Although multiple Model 3152s within one chassis run off a common
clock (CLK10), their outputs are not synchronized to each other. If
the same waveform length and clock rates for two modules are
selected and both are displayed on an oscilloscope, the outputs
may look as though they are synchronized even though they are
not. The waveforms may not start at the same point along the
waveform. If another waveform is selected or if the same
waveforms are reprogrammed, you may notice that the phase
relationship between the two modules has changed again.
CAUTION Phase synchronization requires the use of the VXI ECLTRG0
and ECLTRG1 signals. Other VXI instruments must not drive
ECLTRG0/1 while phase synchronization is enabled.
There are phase synchronization commands that can tightly control
phase offsets between two or more Model 3152s. These
commands are described below. To use the following commands,
two Model 3152s are required. When synchronizing modules, the
waveforms in each module must have exactly the same number of
points.
First, load the waveforms in all the modules in preparation for phase
synchronization. Then select one Model 3152 as master and
program it using the following commands:
PHASe[1]:LOCK ON
PHASe[1]:SOURce MAST
The above Model 3152 is now programmed as master. Next,
program the other Model 3152 modules as slaves (SLAVe) and
program their phase offset in relation to the master. As an example,
program the second and third Model 3152 with 120 and 240 degree
offsets, respectively.
Use the following commands on the second Model 3152:
PHASe[1]:SOURce SLAVe
PHASe[1]:LOCK ON
PHASe[1]:ADJust 120
Use the following commands on the third Model 3152:
PHASe[1]: SLAVe
PHASe[1]:LOCK ON
PHASe[1]:ADJust
240
The three Model 3152 modules are now synchronized