Tabor Electronics 5251, Руководство пользователя

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4
Remote Programming Reference
Arbitrary Waveforms Control Commands
4-33
define and download waveforms to individual segments.
Using this command, segment table data is loaded to the 5251 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 three segments with 12
bytes of data that contains segment size information.
SEGment#212<binary_block>
This command causes the transfer of 12 bytes of data (3 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 4.
The generator accepts binary data as 32-bit integers, which are sent in two-byte words. Therefore, the total
number of bytes is always 4 times the number of segments. For example, 36 bytes are required to
download 9 segments to the segment table. The IEEE-STD-488.2 definition of Definite Length Arbitrary
Block Data format is demonstrated in Figure 5-1. 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.
The segment table data is made of 32-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 32-bit words and rearranged as six 8-bit words
before it can be used by the 5251 as segment table data. Figure 5-4 shows how to prepare the 32-bit work
for the segment start address and size. There are a number of points you should be aware of before you
start preparing the data:
Figure 4-4, Segment Address and Size Example
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 16k
3. Maximum segment size depends on your installed option. With the basic 5251 you can program
maximum 1M in one segment. With the 2M option, you can use the full size of 2 Meg
4. Segment table data has 32-bit values of which are used for segment size. Therefore, Data for each
segment must have 4 bytes
5. The number of bytes in a complete segment table must divide by 6. The Model 5251 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
Parameters
Name Type Description
<binary_block> Binary Block of binary data that contains information on the
segment table.