HP 8530A, Руководство по эксплуатации и программированию, Страница: 337 / 439

HP-IB Programming Basics
read currently selected memory . This transfers the memory data in
real/imaginary pairs .
Data Always Comes from the A ctive Channel
Notice that there are two entirely dierent, parallel, data processing paths shown in
Figure 18-1. One path is for Channel 1 and one is for Channel 2. Each channel has raw ,
corrected, and formatted data arrays . Because the paths are separate and independent,
dierent features can be ON in Channel 1 and OFF in Channel 2. As you have seen, the HP-IB
transfer commands let you select the parameter (1, 2, 3 or 4) for data transfer . But, since each
channel has four independent parameters , which channel will be used during the transfer? The
data transfer always occurs on the A ctive Channel.
A vailable Data Transfer F ormats
In remote programming you can choose one of four binary data formats , or an ASCII data
format. The formats are listed below:
The descriptions of each F orm, below , is provided so you can decide which transfer format is
appropriate for your needs . Specic information on byte sizes and structure of these formats is
provided in \Preparing the Computer to Transmit or Receive Data ", later in this chapter; and
also in the HP 8530A K eyword Dictionary.
F orm 1 (HP-IB Command: FORM1 ). F orm 1 is signicantly dierent from the other four
transfer modes . The biggest dierence is that you can only obtain data from
the R aw Array when you use F orm 1. The other four transfer modes let you
choose any internal data array for transfer .
F orm 1 is the fastest transfer format available , and is almost exclusively used
in F ast CW and F ast IF Multiplexing modes . Refer to \FORM 1" in the HP
8530A K eyword Dictionary for a full description of this transfer format. F orm
1 data can be converted to oating point data in the computer . F orm 1 is the
only transfer format you can use for F ast CW or F ast IF Multiplexing modes .
F orm 2 (HP-IB Command: FORM2 ). 32-bit IEEE 728 oating point format. This format
is not commonly used. It consists of a header , a two-byte number indicating
how many bytes follow , then the real and imaginary data pairs for each
stimulus point.
F orm 3 (HP-IB Command: FORM3 ). This is the recommended format for use with HP
9000 Series 200/300 workstations . It consists of a header , a two-byte number
indicating how many bytes follow , then the real and imaginary data pairs for
each stimulus point. F orm 3 follows the 64-bit IEEE 728 standard format.
F orm 4 (HP-IB Command: FORM4 ). This format is ASCII, and is not as commonly used
as other formats . One of the reasons for this is because it is S L O W. However ,
even with this limitation there are still two good circumstances in which F orm
4 is useful:
When rst learning how to transfer data. F orm 4 comes out in ASCII format
that is meaningful to a human being.
When using GP-IB cards of limited ability . Some third party GP-IB (IEEE
488-2) cards (for PC compatibles) requires ASCII format data.
F orm 5 (HP-IB Command: FORM5 ). This is the recommended format for use with IBM
PCs and compatibles . This is a 32-bit DOS-compatible oating point format.
The HP 8530A K eyword Dictionary describes each form in detail. It also describes the
component pieces of information that accompanies the data.
18-8 HP-IB Programming