Description

Depending on the type of S7-300 compact CPU, various highspeed counters are available up to 60 kHz. They are used for counting and frequency measurement with incremental encoders.

The compact CPUs also offer pulse outputs for pulse width modulation for direct activation of valves, final controlling elements and switching devices. CPU 313C and CPU 314C are also equipped with integrated control blocks that do not reserve any space in user memory. They can be combined with onboard I/Os for simple closed-loop control tasks.

Simple positioning tasks can be solved conveniently in theCPU with the compact CPU 314C. The positioning algorithm for traversing an axis relatively or absolutely according to the rapid traverse/creep speed principle is integrated into the operating system of the CPU.

A 24 V incremental encoder can be connected as the position measuring system. Setpoints can either be output over 4 digital outputs or one analog output ± 10 V.

When positioning, the module first starts the drive (for example, a frequency converter with standard asynchronous motor) by setting an output in rapid traverse. Just before the destination is reached (changeover difference), the module switches the drive to creep feed mode. The drive is shutdown completely when the target position is reached or shortly before this, depending on the parameterization.