Nowadays, measuring and testing equipment are used together with software in order to increase the overall efficiency in making analysis.
The software is usually developed by manufacturers themselves, or in some cases, developed by users who want to see more variety. The program may be developed from multiple languages which often include Visual C++, Visual Basic, Java, MATLAB. However, the most popular language used in connecting Test and Measurement Equipment is Labview, which is a language that is simple to use to develop a program. It is one of the most widely used languages and was developed by National Instrument Co., Ltd.
This article will explain how to use Labview to connect with Test and Measurement Equipment. But before starting the programming, the article will venture to recommend a program which is often used together with Labview after installation. This program is called “Measurement & Automation Explorer” or NII MAX. It is a program used to manage Test and Measurement Equipment connect with computers. It can also test the sending and receiving of information between computers as well as the Test and Measurement Equipment.
Measurement & Automation Explorer (NI MAX)
In using this program, the user must connect measuring and testing equipment with the computer. For the purpose of this article, Hioki RM3544 is connected through USB. After starting the NII MAX program, the screen will appear as shown below (Figure 1).
The connecting port of measuring and testing equipment will appear in Root of Device and Interface, which in this case, appear as USB connection at COM7 Port, as shown in Figure 2. From this window, the user can open VISA Test Panel to set up Parameter or test the sending and receiving of information between measuring and testing equipment prior to starting the program. When the user clicks Open VISA Test Panel, another window will appear, as shown in Figure 3.
From this VISA Test Panel window, the user is able to choose to change communication parameter such as Baud Rate, Databits, Stop Bits and Parity, set up other Parameters for Flow control or I/O Setting such as Termination Characters.
The testing of receiving and sending information between computer and Test and Measurement Equipment can be done by choosing the Input/Output tab on top of the window, as shown in Figure 4.
In receiving–sending information to measuring and testing equipment, the user must know first if the order is for retrieving information or otherwise. The order for retrieving information will have “?” at the end. And the order will also end with “Termination Characters” such as Carriage Return (CR=\r) and Line Feed (LF=\n).
In sending an information retrieving order, the Test and Measurement Equipment will acquire the information in their Buffer. The user must press Read and Write in order to obtain such information. However, the user may choose Query in order to Read and Write with just one press. The other button, Bytes to Read, will provide the amount of information retrieved from the Test and Measurement Equipment. The user can adjust the size if the information size is known.
The first test will be performed with *IDN?\r\n which is an command used for retrieving information such as model number and serial number from equipment to computer. The result as shown in the Figure 5.
In the next test, the measuring value is set to be 30mΩ and the measuring speed is set to Slow mode.
For continuous actions, symbol “:” is used to connect the commands before ending with the Termination Characters. The Termination Character varies from each instruments. The example is using Hioki RM3544. The command for adjusting the measurement duration is RES:RANG and the command for speed adjustment is SAMPle:RATE. Once the symbol ‘;’ is used to join two commands, the command will appear in full as shown below.
RES:RANG 3E-3;SAMPle:RATE SLOW\r\n
When testing the sending of this command with Test and Measurement Equipment, The result as shown in figure 6
The last test is to read the values from the Test and Measurement Equipment sent to the computer. The command to retrieve the measured information is READ?\r\n When the information is retrieved from the measuring and testing tools, the result appears as shown in figure 7.
From the test of sending and receiving information between a computer and the Equipment with the program, it is concluded that program developer can more easily carry out the test for program writing with Labview, which will be discuss in the next article.