Siemens SINUMERIK 840D sl Function Manual page 1055

The switchover of the coordinate system is done via the input signal:
● EB n + 0, Bit 0 (MCS/WCS)
The input signal is evaluated in FC26 with the help of the edge trigger flag. The active
coordinate system is shown in the following output signal:
● AB n + 0, Bit 0 (MCS/WCKS) with 0 = MCS, 1 = WCS
In case of active MCS the traversing key signals of the axes 1 - 6 are transferred in the axis-
specific interfaces (DB31, ... .DBX4.6 and DBX4.7 (traversing key +/-)) of the axes specified
in the machine axis tables (DB10.DBB8 to DBB13 or DBB32 to DBB37).
In case of active WCS it is assumed that the axes 1 - 3 of the machine axis table are geometric
axes. For this reason the traversing key signals:
● Of the axes 1 - 3 (EB n + 2 / 3, Bit 0 - Bit 2) are transferred in the interface of the geometric
axes in DB21, ... .DBB12 + (n * 4), with n = 0, 1, 2), bit 6 and bit 7 (traversing keys +/-) of
the channel specified with the parameter "ChanNo" .
The assignment of the traversing key signals of axes 1, 2 and 3 to the geometric axes 1, 2
and 3 of the channel is permanent and may not be changed.
● Of the axes 4 - 6 (EB n + 2 / 3, Bit 3 - Bit 5) are transferred in the axis-specific interface
(DB31, ... .DBX4.6 and DBX4.7 (traversing keys +/-)) of the axes 4 - 6 entered in the
machine axis table (DB10.DBB11 to DBB13 or DBB35 to DBB37).
No traversing of machine axes in WCS
In case of active WCS (AB n + 0, Bit 0 = 1) the traversing of the machine axes can be locked.
For this, the following output signals are to be set in the PLC user program:
● AB n + 3, Bit 7 = 1 (For WCS: no machine axes)
Requirement to the FC26, not to transfer any traversing key signals for the machine axes.
The traversing key signals for the axes 1 - 3 of the machine axis table are transferred to
the geometric axes 1 - 3 of the specified channel. The traversing key signals for the axes
4 - 6 of the machine axis table are not transferred.
● AB n + 2, Bit 6 (axes 7 - n selected)
Requirement to the FC26 not to transfer any traversing key signals, since the axes 1 - 6 of
the machine axis table are switched over. The axes 1 - 3 are thus not geometric axes, but
instead also machine axes.
Feed override
The value of the HT 8 override switch is transferred as feed override in the channel-specific
interface DB21, ... .DBB4 (feedrate override) of the programmed channel (parameter:
"ChanNo") and in the axis-specific interfaces DB31, ... .DBB0 (feedrate override) of the axes
programmed in the table DB10.DBB8 to DBB13 (machine axis number).
Rapid traverse override
If for the programmed channel (parameter: "ChanNo") the signal DB21, ... .DBX25.3 = 1 (feed
override for rapid traverse) is set, the value of the HT 8 override switch is sent as a rapid
traverse override to its channel-specific. Interface transferred in DB21, ... .DBB5 (rapid traverse
override) and the signal DB21, ... .DBX6.6 = 1 (rapid traverse override active) is also set.
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
P3: Basic PLC program for SINUMERIK 840D sl
13.17 Block descriptions
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