rscott9399
Member
Way to do it in compact logix?
I have had numerous problems with latches
No pretend the bit that is being latched and unlatches is the trigger for some other operation
Its hard to figure why you would do anything this way - but why not get that operation to unlatch when it completes.
Then get the bit latched if it is unlatched.
Your reasoning is flawed. That's not the way a real PLC works. When the CPU evaluates a rung, any Boolean variables that are set or cleared by the rung are in that state at the start of the next rung. If the Boolean variable is tied to a physical output, it is true that the state of the physical output won't match that of the Boolean variable until the physical outputs are serviced.The issue i have found is that the scan time is so fast that the trigger never actually occurs because it cant unlatch itself quick enough before the next rung is latching it again.
You are not allowed to? But can make the scan time slower?
Something is missing in the translation here. btw. You are always allowed to walked off the job. Really.
Your reasoning is flawed. That's not the way a real PLC works. When the CPU evaluates a rung, any Boolean variables that are set or cleared by the rung are in that state at the start of the next rung.
For what you state, the first rung latches then the next rung unlatches, slowing the scan rate wouldn't make any difference. To make sure the unlatch and relatch are noticed in other rungs I would set a It_Was_Unlatched bit and watch that, then if relatched when it WAS OFF set a It_Was_Off_And_Relatched bit.