Fluke PM6681R, PM6685R manual

Each keyword in a SCPI command header represents a node in the SCPI command tree. The leftmost keyword (INPut in the previous example) is the

3-8 Program and Response Messages

Figure 3-7

The SCPI command tree.

The example shows the shortform used in a mix of upper and lower case

SEND→ Input:Imp￿1E6

The example shows the a mix of long and shortform anda mixe of upper and lower case.

SEND→ iNp:ImP￿1E6

For example, an application program may send the following characters over the

R o o tE n d n o d ebus: S u b n o d e s

SCPI command headers may consist of several keywords (mnemonics), separated by the colon character (:).

The common command header starts with the asterisk character (*), for example *RST.

SCPI Commands

In program messages either the long or the shortform may be used in upper or lower case letters. You may even mix up- per and lower case. There is no semantic difference between upper and lower case in program messages. This instrument be- havior is called forgiving listening.

Basically there are two types of com- mands:

Common Commands

ACQuisition:APERture￿<numeric value>

Where: ACQ and APER specify the shortform, and ACQuisition and APER- ture specify the longform. However, ACQU or APERT are not allowed and cause a command error.

This program message consists of two message units. The unit separator (semi- colon) separates message units.

The syntax specification of a command is as follows:

program message unit terminator program message unit

Forgiving Listening

:INP:IMP 1E6;:ACQ:APER

0.1NL^END

Example of a terminated program mes- sage:

The keywords following represent subnodes under the root node. See ‘COMMAND TREE’ on page 3-10for more details of this subject.

Most controller programming languages send these terminators automatically, but allow changing it. So make sure that the terminator is as above.

root level keyword, representing the high- est hierarchical level in the command tree.

Introduction to SCPI