Automated Industrial Load Measurement System - AU Journal

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The complete hardware interface diagram is shown above in figure 5. A 74LS244 line driver IC has been additionally used between the LPT port of the PC and the ADC. This setup has been implemented to electronically isolate the two devices from any disturbances in the connection (e.g., short circuit). Although() not a necessity, it is always a good practice to include such a buffer in the system. Fig. 4. Complete hardware interface diagram Software The main tasks of the software were to – 1. Drive the parallel port for obtaining data from the ADC. 2. Convert the digital data to an analog form to provide the measurement value. 3. Provide an user interface for running the program and manipulating the measurement information. To accomplish these tasks, an algorithm was devised according to the flow chart shown in figure 5. Each process within the measurement setup (e.g., convert ASCII to Decimal) comprises a complex algorithm. Due to space constraints, they are not discussed in detail in this paper. Fig. 5. Flow chart for load measurement system 26
Fig 6 Screen shot of the user interface The user interface of the measurement system looks like the one in figure 6. A few options have been provided for the user of the system. The first option can be selected if the user wants to perform only a single measurement using the system. Option 2 can be used to carry out a succession of measurements with the help of the system. The cumulative measurement value will be displayed in the console when the user decides to end the measurement session. The third option allows setting a predetermined limit for the measurements to be carried out. If the user decides to measure up to a certain weight (e.g., 1,000 kg), then the program will warn the user, both with the help of a text message, as well as an alarm sound once that limit has been reached. This function is extremely useful in packaging industries, where each bag or sack has to be filled up to a certain weight. Discussion A common method of acquiring load measurement data from the load cell is using a microcontroller. This setup ensures that the system footprint is small and portable. The acquired data is usually displayed in an LCD display. While this is a fairly straightforward way of achieving the goal of load measurement, it is not free of certain drawbacks. Firstly, the measured data cannot be stored in a convenient location (e.g., a hard drive) for future referral. Secondly, the system can hardly be made an interactive one, as demonstrated by the system in this paper. And, finally, a microcontrollerbased system cannot be easily reconfigured by the user. As mentioned earlier, various DAQ products are being used in industries for measurement purposes. The hardware can be connected via PCI slots or the USB port of a PC. The corresponding software is supplied with the product or can be downloaded from the internet. They are excellent in terms of ease of use and robustness. However, cost analysis (National Instruments 2006) shows that these attributes come at a very high cost and can be beyond the reach of small scale businesses. This proposed measurement scheme can be implemented in almost all industrial PCs without the need for expensive hardware. Although it doesn’t exactly offer the portability of a microcontroller-based system, it can certainly overcome all the aforesaid constraints. 27
Page 1 and 2: AU J.T. 10(1): 23-28 (Jul. 2006) Au
Page 3: conditioned. A good example is the

Automated Industrial Load Measurement System - AU Journal

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