Table of Contents
Advertisement
User Manual LW120
SEGment#<header><binary_block>
Purpose
This command will divide the waveform memory to smaller segments and will speed up memory
segmentation. The idea is that waveform segments can be built as one long waveform and then just use this
command to split the waveform to the appropriate memory segments. In this way, there is no need to define
and download waveforms to individual segments.
Using this command, segment table data is loaded to the LW120 using high-speed binary transfer in a
similar way to downloading waveform data with the trace command. 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 large number of segment. As an example, the next command will generate two segments with 12
bytes of data that contains start address and segment size information.
SEGment#212<binary_block>
This command causes the transfer of 12 bytes of data (2 segments) into the segment table buffer. The
<header> is interpreted this way:
• The ASCII "#" ($23) designates the start of the binary data block.
• "2" designates the number of digits that follow.
• "12" is the number of bytes to follow. This number must divide by 6.
The generator accepts binary data as 48-bit integers, which are sent in two-byte words. Therefore, the total
number of bytes is always six times the number of segments. For example, 36 bytes are required to
download 6 segments to the segment table. The IEEE-STD-488.2 definition of Definite Length Arbitrary
Block Data format is demonstrated in Figure 4-1. The transfer of definite length arbitrary block data must
terminate with the EOI bit set. This way, carriage-return (CR – 0dH) and line feed (LF – 0aH) characters can
be used as segment table data points and will not cause unexpected termination of the arbitrary block data.
•
<binary_block>
The segment table data is made of 48-bit words however, the GPIB link has 8 data bas lines and accepts 8-
bit words only. Therefore, the data has to be prepared as 48-bit words and rearranged as six 8-bit words
before it can be used by the LW120 as segment table data. Figure 4-5 shows how to prepare the 48-bit
word for the segment start address and segment size. There are a number of points you should be aware
of before you start preparing the data:
1. Each channel has its own segment table buffer. Therefore, make sure you selected the correct active
channel (with the INST:SEL command) before you download segment table data to the generator
2. Minimum number of segments is 1; maximum number of segments is 4096
3. Maximum segment size depends on your installed option. With the basic LW120 you can program
maximum 1 Meg in one segment. With the 4 Meg option, you can use the full size of 4 Meg
4. Segment table data has 48-bit values of which 24 bits are used for start address and 24 bits are used
for segment size. Therefore, Data for each segment must have 6 bytes
5. The number of bytes in a complete segment table must divide by 6. The Model LW120 has no control
over data sent to its segment table during data transfer. Therefore, wrong data and/or incorrect number
of bytes will cause erroneous memory partition
6.
First segment address starts at 256 decimal or 0x100 in hex
7. Compute the start address for segment "n" using the following equation:
ADD
= ADD
n
For example, say you have two segments, the first is 10,000 points. The start address for segment number 2 is
as follows:
Represents segment table data.
+(SIZE
/ 4)
n-1
n-1
Remote Programming Reference 4-49
Advertisement
Table of Contents
