User`s manual
Downloading Data
Directly into the
DAC
This method disables the AFG’s ARM subsystem and immediately outputs
the DAC data point when received. The DAC code received by the AFG
only sets the DAC to output to the received value. It thus does not disables
the AFG’s DAC code format, triggering, marker selection and enabling, and
amplitude setting. Send the DAC codes as Combined lists.
• The lists can be downloaded either in the Signed or Unsigned
number formats, and as Definite Length or Indefinite Length
Arbitrary Block Data.
• Since the AFG stores no data into memory, do not set the last point
bit in the list.
• Download the segment data directly into the AFG’s High Speed Data
Register. The data must go to the register address with a 38 decimal
(26 hex) offset in the AFG’s A24 address space (see Appendix C for
information on registers).
The VXISRCE program shows how to download segment data directly to
the DAC. The program downloads the lists using the VXIbus.
The segment lists are downloaded in the Signed number format and as
Indefinite Length Arbitrary Block Data. The example generates a 0 to +5 V
triangle wave. The frequency of the triangle depends on the speed at which
downloading occurs. The commands are:
1. Reset the AFG
*RST
2. Set the AFG’s Output Amplitude
[SOURce:]VOLTage[:LEVel][:IMMediate][:AMPLitude] <amplitude>
3. Select the DAC Data Format
[SOURce:]ARBitrary:DAC:FORMat SIGNed
This command selects the SIGNed (or UNSigned) number format.
4. Select the DAC Data Source
[SOURce:]ARBitrary:DAC:SOURce VXI
This command selects the source that transfers data to the DAC (see
“DAC Sources” on page 280). Use “VXI” to transfer data using the
VXIbus.
5. Place the AFG Into Hold Until All Commands are Executed
*OPC?
This commands prevents the AFG from receiving data over the
VXIbus until it executes all the previous commands. If
*OPC? is not
sent, the AFG will try to receive data, and thus generate an error,
even before it completes executing the previous commands.
6. Download the Waveform Segment as a Combined Signed List
This step directly downloads the Combined Waveform Segment List
to the DAC using the Signed number format set by the
Chapter 7 High Speed Operation 269