Siemens SINUMERIK 840Di Function Manual page 1645

Note
The unit for the retraction path refers to the current valid unit of measurement (mm or inch).
The reverse stroke is always made in the opposite direction to the current motion. SR/SRA
always programs the value for the reverse stroke. No sign is programmed.
It is also possible to poll the status of an input for synchronous commands of various axes.
Look Ahead is also active for multiple feedrates in one block. In this way, the current
feedrate is restricted by the Look Ahead value.
Application
Typical applications include:
• Analog or digital calipers
• Switching from infeed to working feedrate via proximity switch
Example
Internal grinding of a conical ring, where the actual diameter is determined using calipers
and, depending on the limits, the feedrate value required for roughing, finishing or fine
finishing is activated. The position of the calipers also provides the end position. Thus, the
block end criterion is determined not only by the programmed axis position of the infeed axis
but also by the calipers.
Fig. 2-6
Feeds (V1)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
Depending on whether the external inputs are analog or digital, various feedrate values, a
dwell and a retraction path can be activated. The limit values are defined via the setting
data.
Calipers
Detailed Description
2.3 Feedrate control
2-37