Proximity Switches Get With the Program

Programmable Sensors Have Their Pluses and Minuses

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We have used proximity switches on our dry material handling machines for a number of years. We are now contemplating an upgrade to programmable proximity switches. This should allow us to improve performance by fine-tuning switch characteristics via software. It should also allow us to stock fewer different types of switches. Are these and other improvements worth the time, the trouble and the expense of upgrading from standard to programmable proximity switches?

ANSWERS

Three Factors

There are three factors to consider when evaluating a change from standard to smart proximity sensors: performance gains vs.increased cost, end-user MRO challenges and availability.

  1. Performance gains vs. increased cost. The OEM must consider how the increased cost of the smart switch compares with the improved functionality. This includes the material cost difference between the two devices, the additional time cost of programming the devices vs. standard set-and-forget and the cost decreases from reducing inventory. Only the OEM can answer these questions.
  2. End-user MRO. The proximity switch market is becoming more of a commodity market with each passing year. This is generally due to increased competition and ultimately leads to reduced cost for standard switches. The use of smart switches will not only lead to increased material cost for the end user when replacing one of these devices, but also an increased requirement for maintenance training on how to program the switches. The former can happen often in the material handling industry, while the latter can lead to increased downtime. The OEM should consider both of these points and discuss them with the end user before moving forward.
  3. Availability. The last thing an end user can stomach is not being able to get a switch when the machine is down. This is typically not a problem with standard proximity switches because, as a commodity item, they are readily available from many companies. Smart switches, however, are typically proprietary and difficult to replace between suppliers. This must be factored in over the lifecycle of the machine.

In the end, a good relationship between the OEM and end user will help both discuss and understand the impact of going with smart devices vs. standard proximity switches. Only then can the best decision be made.

Garrett Place
Product Manager, Position Sensors and Object Evaluation
ifm efector

Programmable sensors
Sensors with a preset fixed range eliminate the need to relabel and provide additional tools to customers.

Programming Headache

The hassle that accompanies programming your own sensor outweighs the benefits of properly choosing a sensor with the fixed range at the start. With programmable sensors, the OEM assumes the responsibility of relabeling the sensor and providing the customer with the necessary tools to program a replacement.

Tony Udelhoven
Division Director, Sensors
Turck

Configure It Out

There is a variety of solid-state proximity sensing technologies available to the machine builder for consideration. The most common sensing technologies in use are inductive metal, photoelectric and ultrasonic proximity sensors. These three sensing technologies allow the machine builder to support a wide variety of sensing applications with a limited variety of configurable sensor products.

Rather than having to maintain a large stock of various dedicated sensors for addressing several different sensing applications, a configurable sensor can be easily programmed or adapted by the machine builder to support those different sensing applications.

With configurable sensor products, the machine builder is afforded these sensing considerations: inductive metal proximity sensors with either shielded or non-shielded configurability; photoelectric sensors with configurable diffuse, diffuse with background suppression, polarized retro-reflective or thru-beam sensing functionality and programmable N.O or N.C. output; and ultrasonic configurable proximity sensors for performing inductive proximity sensing tasks, but with a longer sensing range, or, for performing photoelectric sensing tasks where optically challenged with respect to color, transparency, ambient light, condensation or dirt.

The machine builder will find the cost comparison between dedicated and configurable sensor products to be surprisingly similar. Any added cost in replacing dedicated sensors with configurable sensors will be offset by the savings realized in maintaining a smaller replacement sensor inventory.

Craig Eilmann
Product Application Engineering
Schneider Electric

Get With the Program

The upgrade from a nonprogrammable to a programmable proximity switch has many benefits. You will need fewer sensor part numbers in your system, which results in less inventory and a reduced cost.

Manufacture time will also be reduced because of the simpler and faster installation time of the sensor. The less time you have to spend on installation, the more money you will save.

There is less confusion in production with fewer part numbers. It will be easier for the mechanical field representative to exchange one sensor than multiple sensors. This will result in a simpler and shorter installation.

proximity SwitchYou will also be able to be much more flexible in the design of your machine. Sensors can be programmed either at the sensor or externally on the PLCs. The tolerance of the teached switching point on a programmable sensor is much better than a nonprogrammable sensor (less than 5%). The reason for this is that the customer programs the sensor at a certain target distance. In general, a nonprogrammable sensor has a tolerance of +/-10% of the sensing distance. Upgrading from a standard to a programmable proximity sensor would be well worth it.

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