Measuring Circuit Monitoring And Alarm Processing; C Axes To Spindles - Siemens SINUMERIK 840C Installation Instructions Manual

12.93
12.15.3

Measuring circuit monitoring and alarm processing

• The functions pulse code monitoring and zero monitoring are either active or inactive for
both measuring systems (selection made via MD 1820*, bit 1 and 6).
If an error is detected in one of the two measuring systems, the associated alarm is
triggered (alarm 140* "Pulse code monitoring", alarm 144* "Zero mark monitoring").
They are acknowledged with the RESET keys.
• The absolute encoder error alarm 1040* "Absolute encoder defective" and alarm 1044*
"Battery absolute encoder submodule" are also triggered irrespective of the measuring
system currently active.
• Measuring circuit monitoring for alarm 132* "Control loop hardware axis" and alarm 136*
"Contamination measuring system" are only active for the active measuring system. This
makes it possible to change the encoder on the inactive measuring system without having
to carry out a warm restart of the control. If one of these errors still exists when the other
measuring system has been selected, the alarm in question is triggered.
12.15.4

C axes to spindles

For the function C axes to spindles, the second measuring system has a different definition.
Here the first measuring system is the axis measuring system parameterized in MD 400*. The
second measuring system is defined in MD400* via the spindle machine data. Any additional
second measuring system defined in the axis machine data is ignored.
The measuring system parameterized in MD 200* (first) is permanantly assigned to a spindle
with C axis for C axis operation, the second measuring system is used for the spindle
operating modes and must be parameterized with MD 400*. C axis/spindle are assigned in
MD 461*.
Control bit "Measuring system 1/2" in DB32 can also be used for C axes, however the
switchover tolerance MD 1216* has no effect. If the control signal is kept to "1", the mode
controlled measuring circuit switchover spindle C axis measuring system is disabled. This
means that
• if a reference point approach is executed with the C axis, synchronization is with the
precision of the spindle encoder,
• the limit frequency of the spindle encoder remains active, i.e. C axis mode with higher
feedrate is possible.
The spindle encoder (MD 400*) is always used in the spindle modes, i.e. the switchover signal
only effects C axis mode.
If different encoders are being used for spindle and C axis mode, please ensure that the
control directions of the axis and spindles are parameterized in the same direction of rotation in
MD 564*, 1 and bit 2 and MD 520*, bit 1 and MD 521*, bit 1. The correct parameterization
Bit
cannot be ascertained by the system software from the MD bits. The spindle direction of
rotation can be reversed from the PLC with the interface signal "Invert MD 3/4".
For backlash compensation and lead screw error compensation the following applies: if spindle
and C axis encoder are different, backlash compensation and lead screw error compensation
are only active in C axis mode (for first measuring system), if identical encoder definitions have
been entered for the spindle and C axis, backlash compensation and lead screw error
compensations are active in the position control mode M19 (M19 absolute, M19 through
several revoltions) and C axis mode.
© Siemens AG 1992 All Rights Reserved
SINUMERIK 840C (IA)
12.15.3 Measuring circuit monitoring and alarm processing
6FC5197- AA50
12 Functional Descriptions
12–117