Very Basic Ladder Logic Question

[Paul11]

Hi,

I was a very basic ladder logic question. At the moment I can only force on outputs on from the  PLC . My latches do not seem to be working correctly. When I activate the start pushbutton when in online mode the  green light output is not activated. I know the output works when forced the output to a 1 the green light turns on. 

Sorry total new to PLC programming and just trying to get to a handle of it.

Any help at all would be great.

Thanks, 

 

 

[Flex727]

Do you have power flow all the way to the "Automode" coil when in online mode (i.e. are "Auto_Selector_5", "Stop_2_PB", "Emergency Stop" all closed and "F1_Overload" open)? Is "Start_1_PB closing?

Is this in a subroutine? If so, is it being called in the Main Routine?

[gerard339]

You need to change the 'automode' which is in parallel with 'start_1_pb' to 'Green Light' 

[Paul11]

1 hour ago, Flex727 said:

Do you have power flow all the way to the "Automode" coil when in online mode (i.e. are "Auto_Selector_5", "Stop_2_PB", "Emergency Stop" all closed and "F1_Overload" open)? Is "Start_1_PB closing?

Is this in a subroutine? If so, is it being called in the Main Routine?

Hi, thanks for your help,

I have power all the way to the coil but it's not activating.  Should automode that is in parallel with start_pb be an internal bit or a output. I have it as a an global tag. It is the main routine.

Again thanks for the help,

[Flex727]

What you have should work. Make sure there is only one instance of the "Automode" coil.

[Paul11]

I should have the green light come on. At line two. It is energised right up to the coil but not the coil itself? Sorry the third line of code a duplicate of line one that was attached in error.

[Saragani]

Are you sure that the function that has that code is being called?

If yes, are you sure the CPU is running?

 

 

[Paul11]

Ya I'm sure they CPU is running. I can force on the all outputs but not through the code. I've even tried th code -Start pusbutton with  output green light. The green light is not operating. This is the way iv have entered my outputs?

[Flex727]

Make sure there is only one instance of the "Green Light" coil.

[RobertU]

1. Green light is called somewhere else where is turned off
2. Subroutine isn't called
3. Try "download all" and check the result

[Ausman]

I'm not into Unistream at all, but is there an "Initialise and Reset" somewhere?  If none of the above in Flex and RobertU are true, perhaps it is something that simple...it is stuck on old info somehow.

cheers,

Aus

[Cam]

Or if you have made lots of program changes with multiple down loads try downloading a blank program into the unit, reboot it and then put your program back in.