Specifications

User Manual 301/302

Using the DMA

DMA data transfer is the fastest way to get waveforms to the Model

301/302. In DMA mode, the internal CPU disconnects from the

waveform memory and passes access to the GPIB. The internal data

bus is connected directly to the GPIB data bus, and data is

downloaded into the memory in binary blocks. Bytes and bit order are

the same as for the Arbitrary Block transfers as shown in Figures 3.15

and 3.16 except, low-byte is sent first and high-byte second. After the

data is loaded into the Model 301/302, control is returned to the

instrument.

The instrument has to be told when to receive data, send data,

surrender or gain control. DMA commands are explained below.

To write to a segment, you must first define it using the

TRACe:DEFine command. The trace must then be selected using the

TRACe:SELect command. Refer to Loading Arbitrary Waveforms for

more information.

The command:

DMA {(OFF) | ON] (OFF is automatic with the last word)

places the Model 301/302 in DMA state when ON is selected. After

this, the instrument cannot accept normal commands. Data must be

sent to the generator from the host computer. Normal command mode

is resumed when the DMA state is terminated. The DMA state is

terminated automatically to DMA OFF when the most significant bit of

the high byte is set to “1”. Therefore, your last waveform point must

contain DMA termination code as explained above.

The following sequence should be used for DMA data transfers.

1. Controller sends commands:

TRAC:DEF (n),(m)

TRAC:SEL <n>

DMA ON

3. Use an I/O routine such as ViMoveAsync (from the VISA I/O

library) to transfer binary blocks of data to the generator.

4. Last waveform point is sent with high byte’s MSB bit set to “1”

DMA transfer is completed and CPU resumes control.

Using WaveWiz to

Generate

WaveWiz has the ability to produce arbitrary waveforms in 5 ways.

Configuring The Instrument