# Overview

## Task

The function for forward/backward motion on the path permits backward motion along the originally programmed path by means of a real-time signal when the NC program is active. Backward motion is terminated by resetting the real-time signal. Forward motion is then resumed.

## Properties

Different modes are possible with forward/backward motion and they can be set over the PLC interface. They include suppressing the synchronisation of M/H functions or skipping program sections. Restrictions must be observed for certain functions of backward motion. They are described in detail in the section "Known restrictions".

Forward/backward motion on the path can be used for:

- Plasma cutting: Clean nozzle and switch extinguished torch back on
- Erosion machining: slit width compensation

## Parameterisation

The exact response for forward/backward motion can be configured in the start-up and channel parameters. A complete list of parameters described in this document is contained in the section Parameter.

## Programming

In the NC program the command #OPTIONAL EXECUTION... flags a sequence of NC blocks as non-executable in forward/backward motion mode.