Computer Drive Installation Instructions

12 Functional Descriptions 04.96

12.20.7 Retraction

12.20.7.1 Retraction as open-loop control function

The reaction to detected retraction events can be parameterized:

• Switching of outputs on mixed I/O module

• Traversal of an internal retraction with the axes programmed for this purpose

• Output of a mode group stop alarm

• Output of PLC NS signals.

The following diagram shows the sequence of retraction motions.

In this diagram, the braking process of the current traversing motion and the acceleration

process of the retraction motion are executed in parallel. In comparison to normal sequences,

there are areas missing in the resulting motion and allowance must be made for these when

the retraction motion is executed. This correction is made independently of the G90 or G91

characteristics of the retraction motion.

Parameterizable/programmable retraction as open-loop control function

Retraction

motion

Resulting

motion

Interrupted

traversing motion

Notes:

• The open-loop-controlled retraction process must be enabled via NC-MD 529* bit 1 and

NC-MD 592* bit 2 (assignment to source).

• Up to 5 axes in the interpolation grouping and one further spindle (maximum) as well as up

to 5 endlessly turning rotary axes can be programmed for the internal retraction reaction

which, in the event of an error, execute a specific retraction motion.

• A retraction is executed only if the pulse enabling command from the PLC was set at the

instant the error occurred. The speed controller enabling command is specified internally

by the system (control to drive). The terminal connections can be provided by the user via

outputs (e.g. of the mixed I/O).

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SINUMERIK 840C (IA)