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Comments 1. GENerator Digitizer Configuration. Channel 1 of the GENerator
digitizer is CONFigured for 10 readings on the 5V range. The arm source is
set to TTLT0. This VXI backplane trigger line is controlled by the INSerter
digitizer which feeds its READy signal to arm the GENerator digitizer after
its readings are complete. An arm delay of 50
µs is specified to allow for the
INSerter digitizer to switch to the pipeline mode after its readings are
complete (see the "Insert" mode description under "Local Bus Modes" in
Chapter 3).
The INSerter digitizer’s READy signal goes high when the readings are
complete and the digitizer enters the idle state. In order for the GENerator
digitizer to arm on the low-to-high transition, the GENerator digitizer must
be set to accept a positive slope. This is done by writing to the digitizer’s
Arm Source register and setting the slope bit from negative (1) to positive
(0).
The digitizer’s Local bus configuration begins by resetting the Local bus
chip. The Local bus mode is set to GENerate and the feed (data source) is
set to CONVerter:CHANnel1.
2. INSerter Digitizer Configuration. Like the GENerator digitizer, the
INSerter digitizer is CONFigured for 10 readings on the 5V range. The
INSerter digitizer’s arm source and trigger source are INTernal. The
INSerter digitizer transfers (feeds) its READy signal to the GENerator
digitizer over the VXI backplane TTLT0 trigger line.
Again, the digitizer’s Local bus configuration begins by resetting the Local
bus chip. The Local bus mode is set to INSert and the feed (data source) is
set to CONVerter:CHANnel1.
3. Digitizer Sample Rates. The maximum Local bus transfer rate is 80
MBytes/second which is equivalent to 40 MSamples/second. The sample
rate for both digitizers as set by the CONFigure command is 50 ns
(20 MHz). Thus, data is transferred from the two digitizers at a rate of 40
MSamples (80 MBytes)/second.
4. Initiating the Digitizers. After the memory card is configured, the card
is INITiated first so that it is ready to receive the digitizer readings. In a
configuration with multiple digitizers in the INSert mode, the GENerator
digitizer is INITiated next so that it is waiting for an arm signal to begin
taking measurements. When the INSerter is INITiated it takes its readings
and then arms the GENerator digitizer. *OPC? is used to allow the
GENerator readings to complete and be transferred before they are retrieved
from the memory card.
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