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Emil

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Posts posted by Emil

  1. Do you need to apply energy to keep the pressure on level? If so, maybe you don't need ot "touch" the exhost valve and operate PID only pressure filling one. My advice is to set relativelly high values for Pb and Ti. Maybe even Pb needs to be above 100%. Usually pressure control is very fast. When you set "slow" PID, you can control the system.

    One good idea is to use HSO. With relativelly high frequency - let's say 100 Hz or more, you can use PWM. This way you will hold the valve proprotionally open and will obtain very precise control. If you want to implement this idea, please don't forget to connect reverse diodes to the valves. Without them it wil lnot work.

  2. hou need ot make a buffer - another MI. At power up or start specified process, you store the value of MI in thhis buffer (ordinary Store direct). Next scan (net before the one described above) you compare the value of MI with the one of the buffer (Compare function - not equal) and if this is true, activate a bit. Then, the next net (as desctibed above, you will store the curent MI in the buffer. This way the next scan you can compare and locate changes again.

  3. Hi Shargy,

    I made such application long time ago. PID is a quite good option. You need ot set the full open time of the valve in resoluion of 0.1 sec as CV max (CV min = 0).

    Then, you will define register Virtual Valve Position (VVP). There you will store curent valve position.

    During PID operation, you will compare CV with VVP and will give pulse to digital outputs to open/close valve. The length of the pulse will be the difference between CV and VVP.

    In U90Ladder > Help menu > Examples > PID you can find a working example with this logic. Many peopel in the world already used this example and obtain quite good results.

    In case you use Vision - the logic is exactly the same!

  4. First of all - yo have SB8 to prevent you about battery status. So you can prevent situation, where the data will be lost.

    If anyway you want to prevent any case of data lost, just idea I performed in some projects:

    You can define Data table as Part of Project. The data there will be stored in FLASH memory, whicy is battery independent.

    In this data table you can define a list of important parameters with, let's say one column for "Name", another column for Min, another one for Max and the last - for default value.

    Then, you can make a power up subroutine, which will read the data from this DT, will compare with the value in relevant register and if it's out of range, load the default value.

    Just idea...

  5. We were able to simulate the problem here. Our R&D repaired it. We expect to issue the improvement with the comming very soon VisiLogic V9.3.1 and comming with it OS.

    Meantime - very simple temporary workaround - set PID output range to 998 (with 999 the problem still occure). I guess 0.2% of the power will not make any visible change in the system.

    Anyway - very soon te fix will be realized.

  6. Hi,

    Do you have a good sense of humor? If yes:

    Your question seems like "How can I drive my car 100 km/h forward and in the same time 80 km/h reverse?" :rolleyes:

    Seriously - you want to run the same port, in the same time, two totaly different protocols! Sorry, this is just not possible.

    You can use V120-22-RA22 instead. This model has exactly the same I/O and pinout (the I/O card inside in fact is the same), but has graphical display, about 20 times more memory and is about 20 times faster. For you the key is, that it has two independend COM ports, so what you want to perform is absolutelly normal with it.

  7. Hi Damian,

    The choice of stages is 1, 2 or 3 - not so big choice. Usually Autotune is preformed onece in a life, when you debug/tune your system. I understand there are anyway situations, when exchanging the value of one MI can be easier than download relevant DLU. But, based on my experience, in 99.5% of the cases the people will mess, will put illegal value there and then will ask need to understand why it doesn't work?...

  8. Hi,

    You can check the memory dedicated to FB (8kB total) in VisiLogic > View menu > FB Information > RAM allocation.

    In any case, the program don't need to "crash".

    Which version of VisiLogic you're working?

    What exactly happens, when the software "crashes"? Is thhere any specific message?

    Can you send the print screen of the "crash" mesage and your application ot supplrt@unitronics.com? And, of course the softwasre version.

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