Analog or digital outputs | Interfaceforce

Interface sells a variety of instruments designed to capture data measured on a load cell or torque transducer and convert it into a readable form. Within this extended Interface device family, two types of output methods are available: analog or digital. Analogue output for test and measurement equipment is by far the most popular. Analog output is a measurement presented in a continuous stream. Technologies have driven a growing demand for more advanced data collection. Digital instruments use digits as output, providing greater measurement accuracy and digital resolution.

It is important to know which output is best for your project in order to obtain the correct communication capabilities for the intended sensor components. It is an important consideration whether you are designing a new test system or working with an existing program and adding new instruments. For more insights, watch our “Instructional on Instrumentation” webinar here.

Here is a brief explanation of the difference between analog and digital instrumentation, along with the benefits of each.

Advantages of digital
Digital outputs are becoming increasingly popular for several reasons. Firstly, they often have lower installation costs than their analogue counterparts. Digital also works across existing networks. For example, if you have an Ethernet IP address, you can connect it directly instead of running analog signals. Digital outputs are also much more scalable than analog ones, as sensors can often be replaced without problems. Multiple sensors can also be daisy-chained into a single cable run, meaning the user can piggyback into an existing network rather than running cables back to a controller. This is one of the reasons why installation costs are often lower.

There are also built-in fault detections with digital outputs to detect things like open stretches and bridges. And when you digitize at the sensor, the system is less susceptible to noise because digital signals are immune to natural noise.

Advantages of analog
With all the advantages of digital, why would anyone choose the older analog output method? Analog signals are still faster than digital and much easier to process. In addition, analog systems require far less bandwidth than digital ones. Therefore, if you are in a low bandwidth area, digital output solutions may slow down the network, while analog does not.

It is important to note that many DAQs and PLCs accept analog signals. So if the user wants to stick with what they already have in the house, analog might be a better option.

Choose analogue or digital
When deciding between analog and digital instrument output capabilities, it is important to also consider the following questions:

Are you connecting to an existing network? For example, if it's a CAN bus, you may want to use CAN bus sensors. But if it's purely analog, don't you want to switch everything to digital unless there are other factors driving that move?
Are you connecting to an existing DAQ device? If your system has available analog input channels, you can be happy with the analog output. If not, you may need to add additional channels. Or say the system has an EtherCAT connection, you can use the same data acquisition without adding channels by connecting them digitally.
What's your budget? If your network already has many analog systems, the cost of sticking with analog systems may be worth it. If you need to add channels to your DAQ but you have digital interfaces available, you can save costs depending on the number of channels and sensors you need.
How many sensors are you connecting? If you have a lot of sensors, the obvious answer is digital due to the flexibility it offers and the limited cable runs required. However, if you don't need many sensors, analog might make more sense.