ericn (Customer) asked a question.

February 2, 2024 at 12:36 AM
One Encoder to Three Laser Markers

I have an application where I need to share one encoder among three separate laser markers (Keyence) as a speed reference of the product being marked. I'm not sure about the laser marker's input current consumption, but it might be too much load for a line driver's output (20ma) to simply parallel the signals. I'd rather keep them electrically isolated anyway.

 

I realize that commercial encoder splitters exist, but I don't think I need something that elaborate (or expensive). Two ideas I had:

 

1.) Use four Murrelektronik 52511 optocoupler relays. These have an input current of 16ma, so I'd connect the encoder to the input of relay #1. It can handle up to 200ma load, so it could easily drive the 3 other relays in parallel. Each relay's output would then be connected to each laser marker. This isn't a high frequency application, so the 20kHz spec of those relays is plenty fast.

 

2.) I will also be using a CLICK-PLUS PLC in this application, so I thought I might be able to use one input and 3 transistor outputs to split and isolate the signal. A single rung with an immediate input paralleled to 3 immediate outs. I guess the frequency would be limited by the scan time, but probably good for a few hundred hertz, no?

 

I'm leaning towards the first idea, since I don't need to waste I/O, or worry about scan time. Anything I'm overlooking here, or any other ideas?

 

Thanks, -Eric

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  • PouchesInc (Customer)

    I have tested an optocoupler in a position move just to test and see their accuracy and speed. Not in a real world application, but a test bench. It wasnt the specific Murr model that AD sells, but a Schneider model I had. I found it to be really accurate for something not truly rated for high speed or accurate position moves for transferring pulses. What I found what that the higher the frequency the more pulses of error it had, but up to a few khz the error was only a single pulse, and that pulse was 100% repeatable. After 4-5khz it gained extra 2-3 pulses of error, but again it was around 99% repeatable. So you may find a similar thing with the Murrelectronik models. That might not be a problem for you though, as 1-2 pulses of repeatable error may be of no consequence in a real world distance of what 1 pulse is on your product. I think it is definitely something worth trying given the cost of the setup.

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  • PouchesInc (Customer)

    I have tested an optocoupler in a position move just to test and see their accuracy and speed. Not in a real world application, but a test bench. It wasnt the specific Murr model that AD sells, but a Schneider model I had. I found it to be really accurate for something not truly rated for high speed or accurate position moves for transferring pulses. What I found what that the higher the frequency the more pulses of error it had, but up to a few khz the error was only a single pulse, and that pulse was 100% repeatable. After 4-5khz it gained extra 2-3 pulses of error, but again it was around 99% repeatable. So you may find a similar thing with the Murrelectronik models. That might not be a problem for you though, as 1-2 pulses of repeatable error may be of no consequence in a real world distance of what 1 pulse is on your product. I think it is definitely something worth trying given the cost of the setup.

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    Selected as Best

  • ericn (Customer)

    Thanks for the response. I just wanted to make sure there wasn't something obvious that I forgot to consider. In this application, the pulse frequency is the important thing. There's no counting or position info, so a few missed pulses won't be an issue at all.

     

    I'll definitely buy some and test beforehand, but I appreciate the confirmation that this could be a viable solution. Thanks again. -Eric

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