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PDMM profinet

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I have a PDMM controller, AKD-M00606-MCEC-0000,PDMM be slave device,computer with profinet master device read or write data from   PDMM by profinet ,I did a experiment  ,  I write data to a variable in my PDMM , at the same time ,I  read  the same variable  from PDMM,got a  strange data,there is a  curve in attachment,the red line is the data that write to PDMM,the green line is the data read from  to PDMM   ,  unusually ,  there is a sinking , I don't  know  that what's the  trouble  leading to this phenomenon。


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Hi Vicotrymorn,

You state to write and immediately read the very same variable. Not 100% sure on how you implemented that so here some basic guidelines. 

  • use input slots on the PDMM where you want to read data (Input is seen from the Profinet Master)
  • use output slots on the PDMM where you want to write data (Output is seen from the Profinet Master)
  • Copy the written value (output) to a new variable linked to the input

There is an example using a Siemens Profinet S7-1200 controller and the PDMM as Profinet IO Device. Maybe this can help to understand the correct setting for the PDMM.




is there data buffer in PDMM profinet?

victorymorn - Tue, 10/22/2019 - 17:52

Profinet is worked as lower priority task and with a cycle time slower than the PLC normally. The variables linked to the Profinet data are worked in the PLC cycle this could lead to a situation where it seems like there is a buffer, but in general no there should be no buffer.

Martin Rupf - Thu, 10/24/2019 - 07:24

can improve priority for profinet in PDMM?

victorymorn - Thu, 10/24/2019 - 20:40

Please keep in mind that Profinet IO and Profinet RT are no hard real time protocol. They depend on Network traffic/structure and do have a none controlled jitter!

I would suggest you get in touch with the supplier of the Kollmorgen Hardware you have, to start a discussion on the design and how to reach your traget with products you have in the best way .

Martin Rupf - Fri, 10/25/2019 - 00:55
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