Interface Signals - Siemens SINUMERIK 840D sl Function Manual

7.3

Interface signals

Axis­specific signals
Despite assignment of a drive to several machine axes, the use of NC/PLC interface signals
remains unchanged. This requires an explicit coordination of access operations to the NC/
PLC interface signals in the PLC user program.
Status signals
The status signals contained in the following bytes are always displayed in the same way for
all of the machine axes involved in the changeover:
DB31, ... DBB92 to DBB95
Control signals
The control signals contained in the following bytes are only active in the machine axes,
which are currently assigned to the drive:
DB31, ... DBB20 to DBB21
Controller enable
The NC/PLC interface signal:
DB31, ... DBX2.1 (controller enable)
is only effective if the machine axis currently has control of the drive:
DB31, ... DBX96.5 == 1 (status setpoint changeover)
Axes without drive control are subject to functional restrictions and are therefore operated in
the follow-up mode. To do this, the control automatically withdraws the controller enable
signals for these machine axes.
Schematic sequence of a setpoint changeover
Initial state: Machine axis AX1 currently controls the drive.
Objective: Machine axis AX2 should assume control.
Special Functions
Function Manual, 09/2011, 6FC5397-2BP40-2BA0
S9: Setpoint switchover
7.3 Interface signals
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