Glossary 
 
Basic logic functions: Appendix 
Function Manual, 11/2006, 6FC5397-0BP10-2BA0 
25 
Inverse-time feedrate 
With SINUMERIK 840D, the time required for the path of a block to be traversed can be 
programmed for the axis motion instead of the feed velocity (G93). 
JOG 
Control operating mode (setup mode): In JOG mode, the machine can be set up. Individual 
axes and spindles can be traversed in JOG mode by means of the direction keys. Additional 
functions in JOG mode include: → Reference point approach, → Repos, and → Preset (set 
actual value). 
Key switch 
The key switch on the → machine control panel has 4 positions that are assigned functions 
by the operating system of the control. The key switch has three different colored keys that 
can be removed in the specified positions. 
Keywords 
Words with specified notation that have a defined meaning in the programming language for 
→ part programs. 
Leading axis 
The leading axis is the → gantry axis that exists from the point of view of the operator and 
programmer and, thus, can be influenced like a standard NC axis. 
Leadscrew error compensation 
Compensation for the mechanical inaccuracies of a leadscrew participating in the feed. The 
control uses stored deviation values for the compensation. 
Limit speed 
Maximum/minimum (spindle) speed: The maximum speed of a spindle can be limited by 
specifying machine data, the → PLC or → setting data. 
Linear axis 
In contrast to a rotary axis, a linear axis describes a straight line. 
Linear interpolation 
The tool travels along a straight line to the destination point while machining the workpiece. 
Load memory 
The load memory is the same as → RAM for the CPU 314 of the → SPS.