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Model 2730A – Function/Arbitrary Waveform Generator
Programming and Interfacing
Block Transfer
Arbitrary waveform data sent in IEEE488.2 arbitrary block format may take two forms: the
definite form and the indefinite form. The essential difference between these forms is that
the definite form contains a byte count, while the indefinite form does not. In both cases,
the format of the command is
:ARB:DATA<ws><preamble><data><terminator>.
The <data> represents the arbitrary waveform data. This field consists of 8 bit bytes sent
in hexadecimal form. Each arbitrary data point consists of two bytes with the high byte
being sent first. When sending data in this way, the value of a data point may range from 8191 (corresponding to the negative peak), to 8191 (corresponding to the positive peak).
The value 0 corresponds to zero baseline. Compare the ASCII, or front panel
representation, which defines data in the range – 8191 to + 8191.
Example: to set a data value to zero, send the Hex bytes
0800
The definite form <preamb4> consists of two fields. The first is a single byte representing
the number of digits in the byte count. The byte count is the second field in the preamble,
and consists of decimal bytes (0-9), which, when taken together, give the byte count. For
example, the preamble
42563
means that the byte count consists of 4 bytes, and that the byte count is 2563 bytes.
The indefinite form preamble consists of a 0 character alone.
Both the definite and
indefinite forms have a '#' prefix in the preamble.
Another difference is that the indefinite form, since it does not contain a byte count, must
be terminated with LF^EOI.
Since each arbitrary data point consists of two bytes, an even number of bytes must be
sent. In the following examples, the data is specified in Hex format with each byte being
preceded by ' \x', in order to show this.
Example of definite form:
:ARB:DATA #16\x8\x0\x8\x1\x8\x2
Here, the byte count consists of one byte only, and the value is 6.
Example to definite form:
:ARB:DATA #0\x8\x0\x8\x1\x8\x2\x0A
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