TTL1 setting versus PLC

I am planning on using two TTL's.  Each TTL will be involved in PLC coding.
 
My question:
 
Once I set TTL1 to 1 with the WebControl browser GUI, does it activate immediately or does it run through PLC code first?
 
rAINER
 

It's set immediately, but its output MAY NOT CHANGE, or MAY CHANGE ONLY FOR A VERY BRIEF TIME.
 
If your PLC code only changes the output on the transition of a condition, it will probably work as you expect.
If your PLC code is constantly writing the output, then setting it via the GUI may have no (discernable) affect.

Thank you, RossW

That helps

Rainer