thnks for ur reply,,!
still confuse which way to go,,
not experience of motion controller and its locally easily availability,,
using ac or dc motor with encoder feedback to plc ..can PLC read its count and instantaneous stop command?? and one more thing that position is not fixed, position depend on work requirement (through HMI).
As was said, a simplistic PLC, such as many built by Delta, is not going to give you any reasonable precision. But we actually don't know what you mean by "precise" either.
A PLC executes a routine in a linear fashion, "Begin here, end there, repeat". The more instructions you have, the more time it takes to go from "here" to "there". If in the middle f that, you tell a motor to go to a position, and try to watch that process while executing other commands, by the time the PLC finishes its scan and comes back to the motion command, it's too late.
A Motion Controller operates differently. It is always watching ONLY the motion aspects of the task and feedbacks from the servos, then fine tuning the commands to the servo drivers on the fly if the dynamics of the load change. A motion control "card" in a PLC rack will be essentially a parallel processor to the PLC CPU, offloading the motion control aspects of the task, and just updating the status to the PLC as necessary.
If your PLC does not have that available, then your definition of "precise" had better be very loose. If you do want precision and you have already invested in a PLC that is not motion compatible, you can get stand-alone servo controllers that are capable of one or two axes of motion, if that's all you need. Delta makes those too by the way.