twidosoft ladder fault

Hello, iv made up a fairly basic program on twidosoft
but random faults keep appearing in it. On simulation and on live mode when running on the plc, as you can see from the screen shot rung 5 output should be a high value.
to cure it i have to rewrite the wrung again at the bottom delete that one, but then sometimes that moves the problem to
Any ideas?

Well, for starters, rungs 5 & 6 are both writing to the same output?

Rung 5 may be attempting to turn the output on, but rung 6 is definitely turning it off.

So this is the better way to do it?
It makes a simple program very complicated does it not, iv not programed like this in the past- iv assumed the logic only looks for high output commands and doesn't force low ones?

The nature of the coils you see as output devices in the ladder is that it describes fully what will happen: if the coil is on then it's explicitly on and if it's not on than it's explicitly off.
This is different than a VB or other type procedural language where if you turn an output on, it stays on until you explicitly turn it off with another command such as Clear Bit or similar.

I would not say it makes the program complicated.

I have controller several devices from several sections of logic and the only way to handle it was to organize an output section where the various needs of the logic were combined to the outputs.

You will find many several threads/posts on this forum where this subject is discussed.

It makes a simple program very complicated does it not,

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No, not if you place both of your logic branches on two parallel rung branches (see attached picture), one time for each, with one common %Q3.2 output. That is the way I would do it to obtain correct ladder logic AND also retain simplicity of construction.

[I have] not programed like this in the past. I have assumed the logic only looks for high output commands and doesn't force low ones?

Click to expand...

Ladder logic does not work like many high-level computer languages, but instead simulates electrical relay ladder logic. An electrical relay is either energized ON (1) or de-energized OFF (0). If all the input devices to the relay coil goes OFF, then the relay output is OFF or de-energized (logic 0). It is a default case of where the output coil goes off due to a lack of power, not from specifically being told to go OFF. In other words, if there is not a TRUE command to the Output, it will be in the default state of OFF or 0.

If you want your ladder logic program to look like the computer languages with which you are familar, then for your outputs, use the TwidoSuite SET --(S)-- and RESET --(R)-- instructions. Set turns the output ON and it stays ON until a Reset turns it OFF. I do not recommend this method, because it adds the very complexity that you were trying to avoid! Also for motors and other moving equipment, SET can keep an output ON through a power outage, restarting the motor unexpectedly.