Siemens Sinumerik 840D sl Programming Manual page 919

Machine coordinate system
A coordinate system, which is related to the axes of the machine tool.
Machine zero
Fixed point of the machine tool to which all (derived) measuring systems can be traced back.
Machining channel
A channel structure can be used to shorten idle times by means of parallel motion sequences,
e.g. moving a loading gantry simultaneously with machining. Here, a CNC channel must be
regarded as a separate CNC control system with decoding, block preparation and
interpolation.
Macro techniques
Grouping of a set of statements under a single identifier. The identifier represents the set of
consolidated statements in the program.
Main block
A block prefixed by ":" introductory block, containing all the parameters required to start
execution of a -> part program.
Main program
The term "main program" has its origins during the time when part programs were split strictly
into main and → subprograms. This strict division no longer exists with today's SINUMERIK
NC language. In principle, any part program in the channel can be selected and started. It
then runs through in → program level 0 (main program level). Further part programs or →
cycles as subprograms can be called up in the main program.
MDA
Control operating mode: Manual Data Automatic. In the MDA mode, individual program
blocks or block sequences with no reference to a main program or subroutine can be input
and executed immediately afterwards through actuation of the NC start key.
Messages
All messages programmed in the part program and → alarms detected by the system are
displayed on the operator panel in plain text with date and time and the corresponding symbol
for the cancel criterion. Alarms and messages are displayed separately.
Metric measuring system
Standardized system of units: For length, e.g. mm (millimeters), m (meters).
Job planning
Programming Manual, 02/2011, 6FC5398-2BP40-1BA0
Glossary
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