User Manual LW120
Waveforms are created using small sections of the arbitrary memory. The memory can be partitioned into
smaller segments (up to 4096) and different waveforms can be loaded into each segment, each having a
unique length. Minimum segment size is 16 points, as long as its playback time is more than 10
µ
s.
Information on how to partition the memory, define segment length and download waveform data to the
LW120 is given in the following paragraphs.
TRACe#<header><binary_block>
Purpose
This command will download waveform data to the LW120 memory without accessing the DMA port. This
command is recommended in places where DMA capability is not available from the controller. It is also the
only way to download waveform data to the LW120 if you are using the RS232 link.
Waveform data is loaded to the LW120 using high-speed binary transfer. A special command is defined by
IEEE-STD-488.2 for this purpose. High-speed binary transfer allows any 8-bit bytes (including extended
ASCII code) to be transmitted in a message. This command is particularly useful for sending large quantities
of data. As an example, the next command will download to the generator an arbitrary block of data of 1024
points
TRACe#42048<binary_block>
This command causes the transfer of 2048 bytes of data (1024 waveform points) into the active memory
segment. The <header> is interpreted this way:
•
The ASCII "#" ($23) designates the start of the binary data block.
•
"4" designates the number of digits that follow.
•
"2048" is the even number of bytes to follow.
The generator accepts binary data as 14-bit integers, which are sent in two-byte words. Therefore, the total
number of bytes is always twice the number of data points in the waveform. For example, 20000 bytes are
required to download a waveform with 10000 points. The IEEE-STD-488.2 definition of Definite Length
Arbitrary Block Data format is demonstrated in Figure 4-1.
"#"
non-zero
ASCII digit
ASCII digit
low byte
(binary)
(binary)
high byte
Start of
Data Block
Number of
to Follow
Byte Count:
2 x Number of
2 Byts Per
Data Point
Figure 4-1. Definite Length Arbitrary Block Data Format
Remote Programming Reference 4-45