MicroLogix is a choice for non-interpolated, trapezoidal motion, both because of its Pulse Train Output functionality as well as its ability to interface with motion hardware. The MicroLogix 1200 has one 20 kHz PTO function which can provide a single axis of motion control. The MicroLogix 1500 controller has two 20 kHz PTO functions which can provide two axes of motion control. The MicroLogix 1200 and 1500 PTOs are independent of each other and can run completely separate and unique motion profiles.
The MicroLogix PTO functionality is consisting of bit, integer, and double integer status and control variables. Each variable is protected by access privileges and accessed via program logic. The type of motion is provided that is needed at a given time, the user only to write the control program to interface with these variables. This implementation method provides versatility in how the PTO functions and the user program can work together.
The command instruction to the main processor to update the corresponding PTO function basically is the PTO instruction. For instance, when the PTO instruction is scanned on a logic rung, the main system processor will update the PTO function file. It allows subsystem of PTO to run independent of the controller scan while still providing an efficient interface for main program to read status and provide PTO data.