Push-Pull Sensor output versus NPN/PNP

[PaulKraemer]

Hi,
I have a label inspection machine that makes use of Tri-Tronics Label-Eye LERC label sensor. This machine processes a continuous series of labels that are adhered to a backing material. The sensor detects the gaps between each label. This is a "fork" style sensor that requires the labels to pass through the fork opening. As we have been processing thicker labels, we have found the small (2.98 mm) fork gap to be problematic.

I am trying to determine if we can replace the Tri-Tronics sensor with a Baumer OL05.I.GP1B.7WN sensor. This is a very similar sensor, but it has a wider (5 mm) fork gap. I am trying to figure out if these sensors are electrically compatible.

The Tri-Tronics sensor has one NPN output and on PNP output. I am very familiar with these output types, as many sensors I have used in previous projects have had these same output types. The Baumer Sensor describes its output type as "Push-Pull", with an adjustable output function that can be set to NO or NC. I am not familiar with this output type.

The photo below is the product sensor connection diagram for the inspection machine (which is currently using the Tri-Tronics sensor. I have also included links to the data sheets for both the Tri-Tronics sensor and the Baumer sensor. If anyone here can comment as to whether the Baumer sensor would be electrically compatible with the Tri-Tronics sensor for this application, I would greatly appreciate it.

https://www.baumer.com/medias/__sec....7WN_EN_20230508_DS.pdf?mediaPK=9068106121246

https://www.ttco.com/media/pdf/Sensors/070-0150_LabelEye-Instructions.pdf

Thank you in advance,
Paul

 

[RedSnake]

The Baumer is a alternating PNP/NPN so you will have 24VDC out on the output when you chose NO normally open if the the input device is connected as in your functional diagram with your input needing a positive signal in and the sensor is detects something.
If it is NC normally closed you will have 24VDC out when it is unaffected and 0 VDC when it detects something.

According to the Tri-Tronics Label-Eye LERC label sensor manual and your functional diagram it is also connected PNP and you will have 24V DC on output/pin (4) on the sensor when detecting something.

But I think you need to read the chapters
2.1.3 Push-pull switching output
and
2.3 Operation of switching outputs
in the Baumer Guideline for Switching Outputs
there are some considerations to make.

https://www.baumer.com/medias/__sec..._Guideline_V1.00_EN.pdf?mediaPK=8999441334302

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[PaulKraemer]

Hi RedSnake,

Thank you for your thorough response. That is a big help. It seems to me like the Baumer sensor will very likely work for us. Looking over the considerations in the Baumer guideline document you sent a link for, (and please correct me if I am wrong) it seems like Push-Pull is often used for fast switching interfaces for data transmission, in which cases line capacitance and the resistance presented by the load might limit your achievable transmission rate, but my suspicion is that being we are just detecting gaps between labels as they are conveyed through a roll-to-roll unwinding and rewinding machine, the frequency at which we would be switching the output would likely be considered slow.

I emailed our Baumer rep to see if we might be able to get a try-before-you-buy demo. Worst case, I don't think these are terribly expensive, so if a demo is not possible, I might just take a chance and buy one.

I appreciate your help.

best regards,
Paul

 

[RedSnake]

You are welcome.

NAFO Sergeant Anna Gr 69th Sniffing Brigade