Chapter 3 Programming Your Universal Counter for Remote Operation

Elements of SCPI Commands

A macro also lets you send variable parameters along with the name. For example, you could have a macro that sets up a measurement channel. One of the variables may be the input impedance, either 50 Ohms or 1 Megaohm. To program this, you would send the macro name along with the impedance value. To assign a variable inside the macro definition, you would replace the normal parameter with a $ followed by a number from 1 to 9. Up to 9 variables can be assigned. When sending the macro, the first parameter would be assigned to the $1 and all occurrences of $1 in the macro. The second parameter would be assigned to $2 and so on. Here is what the macro called ‘setimp’would look like. It changes the impedance on channel 1 to the value assigned to $1 in the macro command.

*DMC ‘setimp’,#212:INP1:IMP $1

To change the impedance to 50 ohms, send:

setimp 50

The above is a very simple example. Macros are best used for a long sequence of commands. A good use for macros is changing the display from one format to another. To change to the limit graph, the following commands must be sent:

:DISP:MENU OFF :DISP:TEXT:FEED ‘CALC2’ :CALC2:LIM:STATE ON :CALC2:LIM:DISP GRAPH :CALC:IMM

These commands can all be replaced by a macro called ‘limitdisplay ’, defined as follows:

*DMC ‘limitdisplay ’,#290:DISP:MENU OFF; :DISP:TEXT:FEED ‘CALC2’;:CALC2:LIM:STATE ON; :CALC2:LIM:DISP GRAPH;:CALC:IMM

There is a finite amount of memory available in the Counter for storing macros. If you find that you are running low on memory,

you can shorten the commands as follows:

1.Do not send the complete path unless it is necessary.

2.Use 1 and 0 instead of ON and OFF for <Boolean> parameters.

3.Use the short form for keywords, INP for INPut, FUNC for FUNCtion and so on.

The above example for switching to the limit display can be significantly decreased in length using these shortcuts:

Programming Guide

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