Agilent Technologies 8935 Series Manual do Utilizador descarregar pdf (Página 64)

64 Chapter 3

O:\Manuals\E6380A_Progguid\Book\Guidelin.fm

HP-IB Command Guidelines

Sequential and Overlapped Commands

IEEE 488.2 makes the distinction between sequential and overlapped

commands. Sequential commands complete their task before execution

of the next command can begin. Overlapped commands can run

concurrently, that is, a command following an overlapped command

may begin execution while the overlapped command is still in progress.

All commands in the Test Set are sequential.

The processing architecture of the Test Set allows it to accept

commands through the HP-IB while it is executing commands already

parsed into its command buffer. While this may appear to be

overlapped, commands are always executed sequentially in the order

received.

The process of executing a command can be divided into three steps:

1. Command is accepted from HP-IB and checked for proper structure

and parameters.

2. Commands is sent to instrument hardware.

3. Instrument hardware fully responds after some time, Dt.

For example, in programming the Test Set’s RF Signal Generator it

takes < 150 ms after receipt of the frequency setting command for the

output signal to be within 100 Hz of the desired frequency. In the Test

Set, commands are considered to have “completed their task” at the end

of step 2. In manual operation all displayed measurement results take

into account the instrument hardware’s response time. When

programming measurements through HP-IB the Triggering mode

selected will determine whether the instrument’s response time is

accounted for automatically or if the control program must account for

it. Refer to “Triggering Measurements” on page 105 for a discussion of

the different Trigger modes available in the Test Set and their affect on

measurement results.

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Agilent Technologies 8935 Series Manual do Utilizador Página 64