Table of Contents
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Using Signed Data to Generate Waveforms
Note
Using the Signed
Number Format
Transferring DAC
Codes in the Signed
Number Format
Determining DAC
Codes in the Signed
Number Format
Chapter 7
Transferring waveform segments as Digital-to-Analog Converter (DAC)
Codes to the AFG is faster than transferring a voltage list. This section
shows how to transfer the lists as DAC codes using the Signed number
format. The DAC codes are transferred to the AFG as a comma (",")
separated list.
The AFG can only accept a single number format at a time. Thus, if the
AFG currently contains Unsigned data and you wish to send Signed data,
you MUST delete the data in memory first before enabling the AFG to
receive Signed data.
This section shows how to setup the AFG to receive DAC codes in the
Signed number format and how to calculate the codes from voltage values.
With the AFG set to receive DAC codes in the Signed number format, it
receives the codes in 16-bit two's complement numbers. Use the
[SOURce:]ARBitrary:DAC:FORMat SIGNed
For outputs into matched loads and with the amplitude set to maximum
(+5.11875V), the following DAC codes generate the following outputs:
Code 0 outputs 0 V
Code -4096 outputs -5.12 V or negative full scale voltage
Code +4095 outputs +5.11875 V or positive full scale voltage
To calculate DAC codes from voltage values, use the formula:
DAC Code = voltage value / .00125
For example, to output -2V:
DAC Code = -2 / .00125 = -1600
The SIGN_DAT program shows how to store a waveform segment
(i.e., points of an arbitrary waveform) into the AFG's segment memory.
The points are stored in the Signed DAC number format. The data is
transferred to the AFG as a comma (",") separated list. The example
generates a 200 point -5 V to +5 V positive going ramp.
command to select the format.
High Speed Operation
225
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