Fluke PM6681R Basic Measurement Method, Individually Synchronized Measurements, Read?, MEASure?

How to Measure Fast

Basic Measurement Method

A basic measurement method for a sys- tem composed of signal sources, measur- ing object, and measuring devices will be a simple step-by-step procedure. This procedure goes as follows:

Step 1: Set up signal sources

Step 2: Set up measurement devices

Step 3: Trigger measurement devices

Step 4: Read data

Step 5: Evaluate data

The above procedure may be repeated as many times as required.

The methods described here deal with how you should do steps 3 and 4 in the best and most efficient way with the CNT-8X.

Individually Synchronized Measurements

This is a method that you should use when you need to start each measurement externally from the controller. The most probable reason that you should use indi- vidually synchronized measurements is that you need to evaluate data in real time and make decisions depending on the ac- quired data. An example of this could be to tune an oscillator by measuring the output frequency and adjust the oscillator depending on the measured frequency.

Of the many available ways to do this with the CNT-8X, three should be men- tioned: READ?, INIT:CONT and GET and MEASure?

￿READ?

The READ? query provides a basic mechanism for this. It ensures that the measurement is started after the counter receives the command. It will also send back the result. The READ? query should be preceded by setting up the counter by using either CONFigure or individual programming commands. This command should be used if no special speed re- quirements exists.

￿INIT:CONT and GET

In this method the trigger function is con- tinuously initiated by the command INI- Tiate:CONTinuous￿1. This gives you the minimal firmware overhead if you don’t change settings in the counter. Set up the counter either by using CONFig- ure, or by using individual programming commands before starting the measuring sequence. Setting up includes switching on the “wait for bus trigger” function with the following command:

ARM:START:LAY2:SOURce￿BUS.

As default, the counter starts a measure-

ment and sends the result to the controller when receiving a GET or a *TRG com-

mand. This method is the fastest way to make individually synchronized measure- ments.

￿MEASure?

The MEASure? query sets up the coun- ter, ensures that the measurement is started after the command is received, and also sends the result to the controller. This command has the highest possible degree of compatibility to other instru- ments; however the command reprograms the counter, and often you need to set up

7-6 Basic Measurement Method