Coil wont come ON

[Matss95]

Hi, the MB 64 wont come on after I press Key 1. I have several of this options in the program and those works fine. If I use just normal Coil it still wont come ON. The Logic above works fine. I just dont understand what can be wrong. Thanks for help.

[DanT]

Hi;

The  Main Program scans the nets from   net 1(Top)   to  Net  X(End)   - Top to Bottom - , deviating only to do called subroutines.

When a Contact Output is used multiple times in the program,   Only the  LAST   Time  Used  Counts because that is when the Scan does the final  determination of the condition of the contact Output  before setting the outputs,  doing housekeeping  and restarting the scan again.

Where else is MB 64 being used?

Subroutines are only  Active when CALLED, otherwise, the subroutine  and all it's internal logic  is ignored.

Dant

 

 

[kratmel]

Please  Find MB64  in your program and post result to the topic.

[Ausman]

And to end all those good comments above this one, all those warnings in the bottom of your screenshot fully explain part of the issue.   Split your nets up so that you only have one coil per net.  Just because it works in one area doesn't mean it is good practice.  Remember that even though the graphical presentation shown to you looks like it will work, the plc might approach it far differently, so the reference to Stl is very relevant.

All your "controls" on the left of the rung can be tallied together near the beginning of your program, controlling a batch of MBs that you use instead.  You enter all your controlling parameters and then will likely be surprised at how many have commonality. This method will likely actually decrease the number of ladder elements, even doing the one coil per net, as you only have the derived MB as the input. 

Learn about some system delays involving HMI screens. 

Is MB70 actually being turned on?  We are assuming that MB70 and MB45 are associated to different displays.

cheers, Aus

[Matss95]

On 4/26/2019 at 10:53 PM, kratmel said:

Please  Find MB64  in your program and post result to the topic.

 

On 4/27/2019 at 12:06 AM, Ausman said:

And to end all those good comments above this one, all those warnings in the bottom of your screenshot fully explain part of the issue.   Split your nets up so that you only have one coil per net.  Just because it works in one area doesn't mean it is good practice.  Remember that even though the graphical presentation shown to you looks like it will work, the plc might approach it far differently, so the reference to Stl is very relevant.

All your "controls" on the left of the rung can be tallied together near the beginning of your program, controlling a batch of MBs that you use instead.  You enter all your controlling parameters and then will likely be surprised at how many have commonality. This method will likely actually decrease the number of ladder elements, even doing the one coil per net, as you only have the derived MB as the input. 

Learn about some system delays involving HMI screens. 

Is MB70 actually being turned on?  We are assuming that MB70 and MB45 are associated to different displays.

cheers, Aus

Thanks, yes MB70 and MB45 does come ON when I go to the different displays