Industrial sensors with diagnostic functionality

Self-Awareness
For monitoring functionality in industrial processes two aspects are relevant: Environmental awareness and self-awareness. Environmental awareness analyzes impacts which are provided by the environment (e.g. ambient temperature). Self-awareness collects information about the internal statuses of (sub)systems. The diagnostic monitoring of industrial processes, which are typically dynamic, is  not as critical as the monitoring of static situations. If you have many signal changes of sensors due to the activity of actuators, with each plausible sensor signal change you can be confident that the sensor is still alive and acts properly. A good example of this is rotation speed measurement of a wheel with an inductive sensor having many signal changes per second. If the actuator drove the wheel to turn but the sensor would not provide signal changes at its output, something would be wrong. The machine control would recognize this and would trigger a stop of the machine and inspection of the situation.

Inductive Sensors with self-awareness

DESINA
For level sensing applications in cooling liquid tanks of metalworking applications inductive sensors with self-diagnostics are often used. The inductive sensors detect a metal flag which is mounted to a float with rod fixation.

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Additionally, to the switching output these sensors have a monitor output which is a “high” signal when the sensor status is OK. In situations where the sensor is not OK, for example when there has been a short circuit or sensor coil damage, the monitor output will be a “low” signal.  This type of so called DESINA sensors is standardized according to ISO 23570-1 (Industrial automation systems and integration – Distributed installation in industrial applications – part 1: Sensors and actuators).

Dynamic Sensor control
Another approach is the Dynamic Sensor Control (DSC). Rather than using an additional monitoring output, this type of sensors provides impulses while it is “alive.”

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The sensor output provides information about the position of the target with reference to the sensor as well as status diagnostic of the sensor itself.

IO-Link
With IO-Link communication even teaching of defined switching distance can be realized. The IO-Link concept allows you to distinguish between real-time process data (like target in/out of sensing range) and service data which may be transferred with a lower update rate (in the background of the real process).

For more information, visit www.balluff.com.

This blog post was originally published on the innovating-automation.blog.

Inductive Sensors for Washdown Conditions

WashdownSensorsWhen selecting the proper Inductive sensor it is very important to understand the type of application environment the sensor will be installed in. In previous posts, I have blogged about various types of sensors and how they fit into the application mix. For example, a welding application will need specific sensor features that will help combat the normal hostilities that are common to heat, weld spatter and impact due to tight tolerances within the fixture areas.

Inductive sensors are also used more and more in aggressive environments including machine tools, stamp and die, and food and beverage applications. Many times within these types of applications there are aggressive chemicals and cleaners that are part of the application process or simply part of the cleanup procedure that also
mandates high pressure wash down procedures.

So, when we have a stamping or food and beverage application that uses special oils or coolants we know a standard sensor is on borrowed time. This is where harsh environment sensors come in as they offer higher IP ratings with no LED function indicators that seals the sensor to withstand the harshest processes. They also will have high grade stainless steel housings special plated electronics along with additional O-rings making them ideal for the most hostile environment.

InductiveWashdownFeatures:

  • High grade stainless steel housing
  • No LED indicator
  • Gold plated internal contacts
  • Additional sealing O-rings
  • Increased IP ratings
  • Higher temperature ratings

For more information on inductive sensors for harsh environments you can visit the Balluff website at www.balluff.us.