HEIDENHAIN TNC 640, User Manual, Page: 378 / 948

Programming Q Parameters | Principle and overview of functions
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HEIDENHAIN | TNC 640 | Conversational Programming User's Manual | 10/2017
Programming notes
You can mix Q parameters and numerical values within an
NC program.
Q parameters can be assigned numerical values between
-999 999 999 and +999 999 999. The input range is limited to
16 digits, of which 9 may be before the decimal point. Internally the
control calculates numbers up to a value of 10
10 .
You can assign a maximum of 255 characters to
QS
parameters.
The control automatically assigns some Q and QS
parameters the same data, e.g., the Q parameter
Q108
is automatically assigned the current tool radius.
Further information: " Preassigned Q parameters",
page 467
The control saves numerical values internally in a
binary number format (standard IEEE 754). Due
to the standardized format used, the control does
not represent some decimal numbers with a binary
number that is 100% exact (round-off error). If you use
calculated Q parameter contents for jump commands
or positioning moves, then you must take this fact into
consideration.
You can reset Q parameters to the status
Undefined
. If a position
is programmed with a Q parameter that is undefined, the control
ignores this movement.