How IO-Link Sensors With Condition Monitoring Features Work With PLCs

As manufacturers continually look for ways to maximize productivity and eliminate waste, automation sensors are taking on a new role in the plant. Once, sensors were used only to provide detection or measurement data so the PLC could process it and run the machine. Today, sensors with IO-Link measure environmental conditions like temperature, humidity, ambient pressure, vibration, inclination, operating hours, and signal strength. By setting alarm thresholds, it’s possible to program the PLC to use the resulting condition monitoring data to keep machines running smoothly.

Real-time data for real-time response

A sensor with condition monitoring features allows a PLC to use real-time data with the same speed it uses a sensor’s primary process data. This typically requires setting an alarm threshold at the sensor and a response to those alarms at the PLC.

When a vibration threshold is set up on the sensor and vibration occurs, for example, the PLC can alert the machine operator to quickly check the area, or even stop the machine, to look for a product jam, incorrect part, or whatever may be causing the vibration. By reacting to the alarm immediately, workers can reduce product waste and scrap.

Inclination feedback can provide diagnostics in troubleshooting. Suppose a sensor gets bumped and no longer detects its target, for example. The inclination alarm set in the sensor will indicate after a certain degree of movement that the sensor will no longer detect the part. The inclination readout can also help realign the sensor to the correct position.

Detection of other environmental factors, including humidity and higher-than-normal internal temperatures, can also be set, providing feedback on issues such as the unwanted presence of water or the machine running hotter than normal. Knowing these things in real-time can stop the PLC from running, preventing the breakdown of other critical machine components, such as motors and gearboxes.

These alarm bits can come from the sensors individually or combined together inside the sensor. Simple logic, like OR and AND statements, can be set on the sensor in the case of vibration OR inclination OR temperature alarm OR humidity, output a discrete signal to pin 2 of the sensors. Then pin 2 can be fed back through the same sensor cable as a discrete alarm signal to the PLC. A single bit showing when an alarm occurs can alert the operator to look into the alarm condition before running the machine. Otherwise, a simple ladder rung can be added in the PLC to look at a single discrete alarm bit and put the machine into a safe mode if conditions require it.

In a way, the sensor monitors itself for environmental conditions and alerts the PLC when necessary. The PLC does not need to create extra logic to monitor the different variables.

Other critical data points, such as operating hours, boot cycle counters, and current and voltage consumption, can help establish a preventative and predictive maintenance schedule. These data sets are available internally on the sensors and can be read out to help develop maintenance schedules and cut down on surprise downtimes.

Beyond the immediate benefits of the data, it can be analyzed and trended over time to see the best use cases of each. Just as a PLC shouldn’t be monitoring each alarm condition individually, this data must not be gathered in the PLC, as there is typically only a limited amount of memory, and the job of the PLC is to control the machines.

This is where the IT world of high-level supervision of machines and processes comes into play. Part two of my blog will explore how to integrate this sensor data into the IT level for use alongside the PLC.

A new angle on rotary feedback

steelindustryTransporting hot materials (ex. steel slabs) from one location to another via a walking-beam is common place in steel manufacturing. In the past, rotary encoders have typically been used to provide the precise feedback of rotary movement for these types of applications. However, optical encoders are prone to failure in harsh environments. Steel mills utilizing walking-beams for material handling have plenty of dirt and particulates in the air as well as produce high shock and vibration. All of these would contribute to an overall harsh environment which would shorten the life of an optical encoder.

Precise position checking and the continuous adjustment of rotational movements are extremely important on the walking-beam. Inclination Sensors are ideally suited for these exact tasks. With contact-free angle measurement, they guarantee maximum precision when the slabs are being transported. Inclination Sensors do not need mechanical coupling in contrast to rotary encoders, are compact and robust, and measure the deviation from the horizontal on an axis of up to 360°.
inclination-axisDowntime at a Steel Mill can cost up to tens of thousands of dollars per hour. The next time you need you have an angular measurement application in such harsh environments, you may want to consider an Inclination Sensor. It will surely be up to the task!

For more information on Balluff solutions for the metallurgy industry, start here.

For more information, visit www.balluff.com.

Angle Sensing & Tilt Detection Solutions

When an application calls for angle sensing or tilt detection there are a few choices including fluid based and MEMS technology Inclination sensors. For this blog entry we will focus on the MEMS technology. MEMS offerings have the option of one or two axis with up to 360° of measuring range. They provide an easy means of directly detecting positions without making contact enabling continuous feedback of rotational movements along the axis. The precise position control and continuous positioning of rotational movements are critical in many applications making them reliable solutions where accurate positioning is a must.

Sensors based with the MEMS technology operate by taking a capacitance differential and converting it to an analog signal. This analog signal is relative to the angle of the sensor in the application. The compact housing sizes are also a great feature offering various mounting options for a wide range of applications.

constructionequipmentMEMS Inclinations sensors can be used in various types of applications. Inclination sensor typically have  robust IP67 ratings making them ideal for tilt protection for cranes, hoists, tractors, expandable mechanical arms and other types of mobile agricultural machines. The Inclination sensor controls and monitors efficient operation verifying the correct positioning needed for reliable operation.

It is not uncommon to see MEMS style inclination offerings used in the renewable energy market. You can commonly see applications where inclination sensors are mounted directly to a rotating shaft to provide angel feedback for Fresnel Solar Panels.

inclinationsensorProduct Features:

  • Compact housing
  • Low temperature drift
  • Contact Free operation
  • High repeat accuracy
  • Precise analog measurement
  • Shock resistant

Applications:

  • Cranes
  • Hoist/Boom Trucks
  • Lifts
  • Mobile Implements
  • Shaft rotation
  • Solar Power

For more information on inclination sensors visit www.balluff.us.