Bit Setting Limit in RSLogix 500

[bob_g]

I wrote a program for a SLC5/05, downloaded it and it won't set the bit when I'm online with the program. Is there a limit to the addresses that bits can have? Do bit addresses have to be unique, meaning I can't have two coils with the same bit address on different rungs? The logic kinda looks like this:

-----------| |------------| |-----------------------------( )--
I:1/1 I:1/2 B3/93

When online with the program I can see that inputs I:1/1 and I:1/2 get "energized" when the input is activated but the coil B3/93 never energizes. I have a couple other rungs below where the coil has the same bit address. Is this the problem? I thought I could do that. I have other bits in the program with higher unique addresses like B3/177, B3/188 and so forth and they work fine. What am I doing wrong? I'm kinda new to all this and any help you could give me would be greatly appreciated.

Thanks

 

[Ken Moore]

The output coil should not be used in more than one location.
The rung you are looking at may be true, but the one later on is false, so the plc will go with the last one, always. The plc scans the ladder and then updates the image file, since the later rung is false, the output coil is false.

You should combine the logic in parallel branches both "feeding" the same output.

Something like this:

----]  [------------]  [------( )--

                               | 

----]/[------]  [---------

edit: never can get the ladder to look correct.

 

[bob_g]

Ken's the Man!

Thanks Ken that makes total sense. I should have known that. I really appreciate it. Yeah I would have paralleled that rungs together but the preceeding rungs are very long and paralleling them might be a pain.

I guess I'll just give different addresses to the bits and parallel them in a later instruction to set a bit essentially like your saying.

Yeah you are right edit didn't get the rung to look right and I tried like 5 times.

Thanks again