question???

hi...
i have been workin in a proyect of automation of a little packing machines, she were mechanics..and the automatic version that i design is pneumatic and she has an twido programable controler of sneider ..but i have a problem..i have asignated the exporation mode as periodic to 4mS of execution time, for to calculate and ajust the cadence of de machine ( the cadence is the velociti of packing the machine) but , the execution time real is 3ms and the PLC operates how the exploration mode were ciclic and no peridoc..and i don't know
how to adjust this .
Thank you
the first machine...the pilot ..is in test.. and this is operaratin veri good..but the calculate values for the cadence ajusments aren't exactly ..and if i connect a MMI dialog terminal to de machine the perforamnce the ajusment to the opertor aren't the best.
thank you

When using timers... in any PLC, they will work "when there time comes".

This means that when the PLC central "Brain" is finish with its own stuff... he takes time to drive whatever these timers are set to drive...

The "Master of the unviverse" sitting inside the PLC does not "interrups" what he is doing just to execute something that a timer tells him to drive.

If you want to "interrup" Mister Da Brain... you will have to program...

What else ... an "interrup"

Look at it in the book of your PLC.

timing

if you use a terminal or hmi the plc will slow down as it needs to send data to the terminal.
so make it as fast as possible, and make the proces without timers as these need to be adjusted when speed is changed.
try it different approach
i use external timers when adjustment is needed so program needs no hmi.