RSLogix 5 instucion set

[hydin]

In my logic I have a instruction set(GEQ)that has a branch shunted around it.
I am not sure why this is, does that bypass that instruction set allowing the next instruction set to operate even if the previous one isn't true?

 

[usuallyconfused]

Yes it will. And although it's not good practice you'll find it used a lot. Typically, it's used for troubleshooting and forgoten about. Or a quick fix or work around that was never redone correctly.

 

[hydin]

Thanks

 

[jtn]

I always make an always on bit and an always off bit with my name in the comment whenever working on a PLC. I disable rungs with the always off bit, and put the always on bit in the shunt around logic I want to bypass. When the process is working and everyone is happy I search for these two bits and take out what ever logic is bypassed or disabled. It's a good way to remind myself what still needs some housekeeping before I leave.

 

[rstech]

I always make an always on bit and an always off bit with my name in the comment whenever working on a PLC. I disable rungs with the always off bit, and put the always on bit in the shunt around logic I want to bypass. When the process is working and everyone is happy I search for these two bits and take out what ever logic is bypassed or disabled. It's a good way to remind myself what still needs some housekeeping before I leave.

Ditto but I only use Always False bit.

 

[jkerekes]

Good idea. There was a time with Rockwell software that you couldn't search for shorted branches either. Made finding them extremely difficult!

 

[jtn]

I don't use the built in bit because other people may have used and then it leaves with the possibility of thinking that I was the one who made that change when someone else may have actually done and are still tinkering with it. If I have a set of bits that I know only I used it takes that possibility out of the equation.

 

[daba]

I used to be a senior engineer responsible for the "creation" of large projects, employing a "team" of engineers.

I made sure that I could at least have a stab at policing what was going on.....

1. I banned AFI instructions.

2. I banned shorted branches.

Each programmer had his own "bit" (bit address in SLC/PLC5, tag name in ControlLogix. There was a rung of code that reset/unlatched all of those bits/tags, so they could use XIC (as AFI), and XIO *(as "Always True")

Each day I could cross-ref these flag-bits to see what each programmer needs to work on.

I made them use these flags, and it was as good for them as it was for me - helped to eradicate "forgotten" tweaks, resolutions, rewrites....