22mm keyed potentiometer

Here is a link to a Siemens IO Link documant that shows a RFID cylindrical key style authorization level system on Page 2.

Been looking for link for the switches - i thought i saw them on display at my Rockwell distributor, but haven't found them on their website yet.

Allen-Bradley, if they still exist



800T-U19 Potentiometer
800T-N163 Locking Attachment




https://forums.mikeholt.com/threads/lockable-potentiometer.77426/

This kinda stuff is hilarious. How can we engineer equipment so idiots cant F it up?

Unfortunately I spend lots of time dummy proofing.

Ive got myself in a bit a trouble before for this suggestion: Fire the first dummy that breaks the rules, and dont hire any more dummies. Problem solved.

That said, I am a fan of protecting pots. From accidental damage, accidental adjustment, and, of course, unauthorized adjustment. I personally like the lockable flip cover. If you are still worried about damaging that you should rethink pot location or even panel location.

James42005 said:

and dont hire any more dummies. Problem solved.
.......
If you are still worried about damaging that you should rethink pot location or even panel location.

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I was told long ago I was greatly underestimating the quality of idiots HR was hiring when i worked at a stamping plant.

As far as 'damage' I was thinking more of intentional "I am going to get to that pot" action by the operators. That thin plastic Amazon cover would not last 10 minutes in the stamping plant mentioned earlier.

Aabeck said:

"I am going to get to that pot" action by the operators. That thin plastic Amazon cover would not last 10 minutes in the stamping plant mentioned earlier.

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Then I most certainly stand by my comment about firing the first "example".

James42005 said:

Then I most certainly stand by my comment about firing the first "example".

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We are an OEM building panels for the machine manufacturers. Neither we nor they have any control over who the end operator will be. They are simply trying to make it easier for the managers at the end customer.

Steve Bailey said:

Keyed switch on the control panel next to the pot. Pot signal wired to a PLC analog input. PLC analog output is actual speed reference to the drive. Logic in the PLC program to transfer the pot signal to the reference when the keyswitch is on, otherwise leave the reference unchanged. Perhaps an illuminated keyswitch to warn the operator of a large difference between the pot setting and the actual reference due to pot twiddling without the keyswitch. That's complicated enough to maybe convince the customer that its easier to accomplish what they want (speed changes only by authorized people) using an HMI.

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A slight variant to Steve's suggestion: Use an encoder with a knob attached instead of a pot. At the moment of "authorization", "sync" the encoder counts with the drive's digital speed reference. If the knob is twiddled it makes no difference unless there is "authorization"

I saw this implemented on a conveyor line with 29 individual motors. The engineer was able to use just one "pseudo pot" for all of the drives (the motor had to be selected first). There were no "end of stroke problems" due to the continuous nature of the encoder. This also allowed fine adjustment like a multi turn pot if desired.

The rugged construction of an encoder was also a plus. In this environment pots only last about a year. The encoder has been in place for more than 15 years.