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There are many different options to consider when purchasing a truck scale. One of those options is digital or analog load cells. Let’s explore the differences and what is the best fit for you.
Let’s first explore what an analog signal is compared to a digital signal.
Analog and digital signals are types of signals that both carry information. Analog signals have been around forever and are mostly used in communication systems, think AM and FM radio. Digital signals represent more sophisticated data that is processed faster and less likely to be disrupted. Think of HDTV compared to your old “rabbit ears” antenna TV (analog signal).
Applying These Signals to Load Cells
Let’s now take what we know about analog and digital signals and relay that into how analog and digital load cells function.
An analog load cell measures the amount of resistance of compression caused by weight being applied and converts it to an analog signal, or voltage. Each load cell is connected to a junction box that sums each load cell’s voltage and transmits the sum to the scale indicator. The indicator then converts the sum to a digital signal and displays the weight.
While a digital load cell technically starts as an analog signal, this signal never leaves the load cell as an analog signal. The conversion to digital happens directly on the main board of the digital load cell and thus the signal leaving the load cell is of higher quality and stays that way. There is no conversion needed later on and sometimes a junction box can also be avoided.
When is Digital a Better Choice?
First, because the digital signal is of higher quality, troubleshooting the digital load cell, and consequently any scale issues, is much easier. This can be done remotely via computer or from the scale house itself. The days of a technician measuring the voltage at each load cell or junction box are a thing of the past with a digital load cell.
Second, and related to the first point above, if there is a problem with any of the load cells or the indicator, these components are easy to replace since all of the components store calibration data. Calibration data can be downloaded from the indicator to the new load cell, or from the load cell to the new indicator. In many situations, this can avoid having your local service company come out to fix and/or re-calibrate your scale. Not only does this save serious time but think about the money that can be saved if your on-site maintenance crew can fix scale problems and negate the line of trucks that would stack up while waiting for your service
Third, digital load cells are guaranteed against lightning. If you put a large slab of steel in the middle of a field, it’s going to act as a lightning rod of sorts. The last thing you want is a $5,000+ bill every time a thunderstorm comes through and lightning wipes out your components. Because of the higher quality digital signal, this technology has proven to be completely resistant to any lightning or surge events, provided the scale is properly grounded of course.
And last but certainly not least, the digital load cell is more accurate. What is more accurate you may ask? Accuracy can first be represented by the digital load cell being the first truck scale load cell to be approved in 10lb. increments. Think of this as being able to get more product in a truck or being able to dial in the weight more precisely when filling on the scale. But maybe, more importantly, more accuracy is represented by years of data that shows when these load cells are in the field they can typically go years at a time without being calibrated or adjusted. So when would it make sense to purchase analog load cells you may ask?
When is Analog a Better Choice?
If minimizing your up-front cost is a key factor in your truck scale purchase, you will likely be able to save around 5-8% by purchasing an analog truck scale.
If you would rather keep your existing scale indicator because it has a computer program or custom ticket associated with it, then an analog truck scale might also be for you.
Lastly, although rare, some service companies are not well versed in servicing digital truck scales. It’s best to ask your service company if they are comfortable servicing a digital truck scale before purchasing one. If they aren’t, it might be best to stick with an analog system.
As with all of our articles, we want to make sure you are as informed as possible before making a big decision like purchasing a truck scale. If we can help provide any more clarity on load cell technology please don’t hesitate to contact us.