Siemens SINUMERIK 840D Function Manual page 50

G2: Velocities, setpoint / actual value systems, closed-loop control
2.4 Setpoint/actual-value system
Reference point approach is executed by the selected measuring system.
Every position measuring system must be referenced separately.
For explanations of encoder monitoring, see Function Manual
Section
For explanations of compensation functions for actual value acquisition, see:
Further information:
Function Manual Monitoring and Compensating; Compensations
Switching between measuring systems
One can switch between the two measuring systems through the following NC/PLC interface
signals:
DB31, ... DBX1.5 (position measuring system 1)
DB31, ... DBX1.6 (position measuring system 2)
Further information
See Function Manual Basic Functions; Various NC/PLC interface signals and functions.
It is possible to switch over measuring systems at any time, the axes do not have to be
stationary to do this. Switchover only takes place if a permissible deviation between the actual
values and the two measuring systems has not been violated.
The associated tolerance is entered in the machine data:
MD36500 $MA_ENC_CHANGE_TOL (max. tolerance on position actual value switchover)
On switchover, the current difference between position measuring system 1 and 2 is traversed
immediately.
Monitoring
The permissible deviation between the actual values of the two measuring systems is to be
entered in the machine data:
MD36510 $MA_ENC_DIFF_TOL
For the cyclic comparison of the two measuring systems used, this difference must not be
exceeded, as otherwise Alarm 25105 "Measuring systems deviate" is generated.
If the axis is not referenced (at least in the current control measuring system), then the related
monitoring is not active if MD36510 = 0 or if neither of the two measuring systems in the axis
is active/available.
Types of actual-value acquisition
The used encoder type must be defined through the following machine data:
MD30240 $MA_ENC_TYPE (type of actual-value acquisition (actual position value))
Simulation axes
The speed control loop of an axis can be simulated for test purposes.
50
Axis monitoring .
Monitoring and Compensations ,
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA