Limitations And Constraints; Precedence Of Function-Specific Acceleration; Axis Container - Siemens SINUMERIK 840D sl Function Manual

17.4

Limitations and constraints

17.4.1

Precedence of function-specific acceleration

The protection function only uses the function-specific acceleration of the machine axes
MD63514 .$MA_CC_PROTECT_ACCEL to calculate the time at which deceleration should
be performed. This means that the protection function does not take the current acceleration
of the machine axis in the channel into account.
NOTICE
Path reference
If machine axes being monitored by the protection function are traversed by a channel with a
path reference to other axes, this path reference is lost as soon as the protection function
causes the axis grouping to decelerate. The machine axes being monitored by the protection
function are decelerated using their function-specific acceleration values from machine data
item MD63514 $MA_CC_PROTECT_ACCEL. The remaining axes in the axis grouping are
decelerated using the current path acceleration value of the channel.
17.4.2

Axis container

If the assignment of the machine axes to be monitored changes dynamically during the
course of a machining process - when using axis containers, for example - the protection
function must be deactivated, its parameters reassigned, and then reactivated prior to the
change (in this case, the axis container rotation) being made.
Example
The protection function is to monitor logical machine axes 1 and 13. These relate to slots 1
and 2 of axis container CT1. The associated real machine axes are AX1 and AX13.
In an axis container rotation, the axis container makes a transition by one step, which causes
the real machine axes to be changed.
Machine axis AX13 is retracted in the positive direction of travel. Machine axis AX1 is
retracted in the negative direction of travel.
Assigning parameters for the NC
Logical machine axes: axis numbers 1 and 13
• MD10002 $MN_AXCONF_LOGIC_MACHAX_TAB [ 0 ] = "CT1_SL1" (log. mach. axis 1)
• MD10002 $MN_AXCONF_LOGIC_MACHAX_TAB [ 12 ] = "CT1_SL2" (log. mach. axis 13)
Axis container CT1, slot 1 and slot 2
• MD12750 $MN_AXCT_NAME_TAB[ 0 ] = "CT1"
• MD12701 $MN_AXCT_AXCONF_ASSIGN_TAB1[ 0 ] = "AX1" (slot 1)
• MD12701 $MN_AXCT_AXCONF_ASSIGN_TAB1[ 1 ] = "AX13" (slot 2)
Special Functions
Function Manual, 09/2011, 6FC5397-2BP40-2BA0
TE9: Axis pair collision protection
17.4 Limitations and constraints
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