PLC programming [need urgent help!]

[wowie]

I'm trying to install a security system to the door of a room and I cant get the logic quite right. I also have the MD-HMI keypad so the purpose is to have the person entering the room enter a password on the keypad and have a signal sent to a striker which opens the door. For the people exiting, they should just be able to push a button on the inside and the striker will again open the door. Also, to detect whether the door is open or closed, I have a magnetic strip along the top of the door. If the door is opened, there should be a 15 sec countdown and then a buzzer should go off until door is closed. I've come up with this logic, but I am stuck:



    Keypad                  Magnet                      Striker
|----||-----------------|/|-------------------(OUT)
|  Button      |                                 |            Duration
|----||------                                  ---------(TIM)
|
|
|
|    Duration              Magnet                      Buzzer
|----||----------------|/|--------------------(OUT)
|

The problem with this is that I want the Buzzer to go off only if the Magnetic strip is open(when the door is still open). With the configuration I have, the buzzer is going off if the magnetic strip is closed. How do I make the change? Or is there any way I can specify a condition to block an electrical signal to the buzzer? Any help would be much appreciated!

[support]

I assume the "magetic" input is turned ON when the door is closed and it is turned OFF when the door is open?

Your first circuit is OK. Your second circuit may be modified to the following:


|   Duration                              Buzzer
|----||---------------------------------[Latch]
     Magnetic                               Buzzer
|----||---------------------------------[CLEAR]


When the door is opened and "Duration" timer times out, the buzzer will be activated. When the door closes, the Magnetic input turns ON and the Buzzer output is cleared and therefore the buzzer is turned OFF.

[wowie]

Thanks for the quick reply!  

I'm trying out this new logic right now.
And as for the keypad, I'm pretty sure that's not how we call it right? By the keypad, I mean the MD-HMI. I just drew it as a switch, which I'm sure isnt that simple. For now, I downloaded the sample programs for the MD-HMI and trying to understand how to setup a password security system using these samples.

[support]

You can use the HMI sample program code to accept password entered by user, then compare it with what's stored in the program and if it matches, then turn on a relay called "keypad" which can then fit into the rest of your program.

[wowie]

yes, your logic is flawless.

Thanks for replying and one last question:
I have my timer's set value at 150. And to specify the units, I went to the special bits and clicked on the 0.1s Clock. 150 x 0.1 = 15 seconds. Is this correct?

[support]

The timer unit by default is 0.1s. You don't use the clock pulse to trigger the time. To change time base unit to 0.01s you use the TBASIC HSTIMER command.

Other time base can be constructed using a clock pulse and a counter to make a timer. This is one way of increasing the number of timer or to obtain long timing beyond 999.9s without cascading timers.

[FQ-ONG]

Set value 150 at timer = 15 seconds.

   Input                                     Timer
|----||-------------------------------(OUT)

When Input turn ON, Timer will automatic countdown in 15 seconds. After 15 seconds, Timer will turn ON.

If you want 150 x 0.1 = 15 seconds, you can use counter. Like what the Mr. Support says as previously, using a clock pulse and a counter to make a timer.

   0.1s Clock                           Counter  (Value set at 150)
|----||-------------------------------(CTR)

                          OR

  1s Clock                               Counter  (Value set at 15)
|----||-------------------------------(CTR)

Thank You.