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Thread: Auto logout PLC activity pulse?

  1. #1
    Join Date
    29.01.2016
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    24

    Default Auto logout PLC activity pulse?

    The auto logout facility will of course logout an inactive user.

    An active user will touch the screen, Zenon sees this and resets the internal timer for auto logout.

    However, Zenon is but one small part of the machine. The machine also has pushbuttons, dials, guarding, doors, all of which the present human interacts with. None of these actions reset the internal timer. So even if the operator is present and doing their job, just not touching the HMI, they are still going to be logged out because they should have known to touch the screen.

    How can I easily take an activity pulse generated in the PLC up into Zenon so Zenon can use it as evidence the operator is still present?

  2. #2
    Join Date
    25.08.2016
    Posts
    1

    Default Re: Auto logout PLC activity pulse?

    I would like to know it as well. if anyone know something about Auto logout PLC acivity pulse, please reply fast.

  3. #3
    Join Date
    18.07.2011
    Posts
    138

    Default Re: Auto logout PLC activity pulse?

    Hi.

    So from zenon point of view there is two facts to consider. One is if there was an HMI interaction the other one is if there was some user - machine interaction.
    If there was no interaction for both facts for a given time x the user should get logged out.

    fact 1, HMI interaction: There is a System Driver variable to determine if there was any user interaction called "idle time". It is a Counter counting seconds since last user interaction.

    fact 2, user - machine interaction: zenon cannot recognize any interaction "outside" the scada System. So whenever a user interacts with the machine it has to be reported to zenon by changing a variable value etc.. Means whenever a door is opened, a button is pushed etc. it has to trigger a variable change. This has to be done on machine side. In zenon you configure a counter since the variable value last changed. So you have a variable static counting the seconds. You have a second variable which indicated external user interaction. Whenever the external user interaction is triggered the counter is reset to 0. E.g. this could be done by using a rema triggering a set value function.

    Now combining both variables using the math driver. Using the math driver you have a boolean variable which indicates if both counters exceeded a given time. This is defined by linking fact 1 and 2 to the formula and check if they exceed a certain value. If so the boolean value is TRUE and this value triggers then a user logout function.

    Attached a version 7.50 demo project linked to see how I configured the above described. Fact one is represented by variable "idle time", fact two by variable "extern_user_interaction" which could be set by klicking the switch on the start Screen. A rema resets the counter whenever the switch is pressed.
    If both counters exceed a value of 30 seconds the boolean math var is set TRUE.

    BR
    Attached Files Attached Files

  4. #4
    Join Date
    29.01.2016
    Posts
    24

    Default Re: Auto logout PLC activity pulse?

    This seems very good, thank you.

    I am looking into grafting this system into my project. I can see how I will adapt this to have a variable logout time that will be applied to both the PLC and Zenon projects.

    If I use this method, I will need to inhibit the internal automatic logout in Project | User Administration.

    This might have an impact on 21 CFR Part 11 compliance if I make the variable timeout = 0 seconds. (For 'No Auto Logout')
    I think it is OK if I make sure there is always a logout time.

  5. #5
    Join Date
    18.07.2011
    Posts
    138

    Default Re: Auto logout PLC activity pulse?

    you still could use the automatic logout time though beside the solution discussed, like a backup timeout with 10 minutes e.g.

    If you want to make the logout time dynamic you could link another variable to the math driver formular. The formular checks then against the variable value and not the constant value. This variable could also be communicated via a driver. So you could then change the timeout via the variable value from zenon or PLC side.

  6. #6
    Join Date
    29.01.2016
    Posts
    24

    Default Re: Auto logout PLC activity pulse?

    A different question. In the project you posted here, what is causing the value of "counter" to increment each second?

    I have a need to have a screen disappear after a few seconds, but I don't see how to make a timed counter, then I remembered this project did something like that, but I look in the project. I can see the number incrementing is the variable 'counter' but it seems to be 'magic'.

    There doesn't seem to be a simulation project when I try to open it.

  7. #7
    Join Date
    18.07.2011
    Posts
    138

    Default Re: Auto logout PLC activity pulse?

    Hi.

    For the project sent I used a process driver set to simulation mode. If you check on the "counter" variable you will see that it is linked to the S7TCP driver. This driver is configured for counting simulation so all variables linked to that driver will be incremented every second.

    Another option would be to use an increment write set value function and time control executing this increment function once every second. Attached a screenshot of the write set value function configuration and the time control setting.

    For you usecase the most suitable solution might be using zenon logic timer functions. There is upcounting timers which could be triggered to start counting. Please check out the zenon logic documentation chapter "timers". Docu path also to be found in attached screenshot.

    BR
    Attached Thumbnails Attached Thumbnails timecontrol.png   timers.png   incrementfunction.png  

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