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Need password protection for my PLC when i starts

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Hello everyone!

This is my first post here, as i have a problem regarding a program i have to program ASAP.

When i'm starting my M91 PLC I'm supposed to enter the value "485" before it is possible to start my process. (I'm filling water into a tank through diffrent transmitters)

My question is how i program this into the U90 ladder.

Detailed list of my problems:

When i start the PLC i'm gonna arrive at a starting screen were i have to type in "485" and then press enter to go to the next stage.

I can't start anything before i have entered 485.

When i enter 485 i have 1 minute to start my process, so I imagine the 485 code is a MB that i can reset.

When i hit my emergency stop i have 2 minutes to start the process, if not it goes into the password protection state again.

Anyone know how to do this?

Another question: How do i make a 2sec pulse i can connect to a light? I know there is a SB for 1sec pulse, but I need one for 2 seconds.

Much love, Daniel

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The easiest way to do this I would think is just to make an integer variable on the first screen that you have to enter the value of "485" in the ladder compare that if youenter a value of 485 for the MI you have slected tfor the integer entry then you set a MB that is apermisison bit that is in the front of every other ladder line in the program so that nothing can be executed unless that bit is true. (make the bit reset on startup). In addition if the MB is set start a one minute timer. if your second action is taken set a new MB. Use the new MB between yout first MB and the timer so that the timer will only count down if the second step is never taken. If the timer runs out then reset the first MB and the process starts all over again.

Same thing for the E-stop. just keep adding timers and MBs until the logic of yout program does what you need it to do. (make sure you force the PLC to go back to the start up screen whenever the MB for the original password is not set)

Good luck


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