Keeping the Production Line Up

July 07, 2014

The machine is down. Again.

That one area has been causing your team headaches over the past few months, because if it's not one sensor going, it's another. And now you have to inspect each element in that section to figure out which sensor popped so you can replace it, and then track down the sensor log to program the new part. You can almost see the missed production dollars adding up.

This costly situation is not uncommon, and has plant managers looking for new ways to anticipate trouble spots, then easily reprogram replacement components before they take down a machine.

With these functions in mind, a powerful open communication protocol called IO-Link is gaining popularity as a means of communicating with sensors.

An overview of IO-Link
Typically used in factory automation settings, IO-Link adds functionality to components by gathering important data from them.

Think about IO-Link as it compares to the HART protocol for process automation. In most process plants, communications run via analog signals over two wires. HART superimposes a digital signal over the analog wire, communicating parameters and diagnostics data from lower-level devices to higher-level controls.

IO-Link adds similar parameter and diagnostic functionality to lower-level devices in factory automation -- for example, a basic proximity sensor. The difference is that everything is digital; the IO-Link digital communication signal is imposed over the existing digital data signal from the sensor.

This communication technology can be implemented via IO-Link sensors and junction boxes, or via the sensors alone if the PLC recognizes IO-Link language. To retrofit existing processes, the first option is the most popular. Adding IO-Link junction boxes does not require the changeover of all sensors on the line, which saves time and money, while still enabling the full advantages of the technology.

Digital sensors that include IO-Link technology are available for most applications and can be implemented on new installations, or, they can replace existing sensors on the line. Once formatted, diagnostic and parameter data are available.

For example, a plant might be looking to gather specific data from its temperature sensors. Traditionally, the sensors will trigger a digital output to turn a heater on if the temperature gets too low. However, there is no measurement of the exact temperature of the installation.

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