Siemens SINUMERIK 840C Installation Instructions Manual page 322

12.93
Bit 0
Note:
In machining channels bit 0 must always be "1".
NC MD
542*
All auxiliary functions M, S, T, D, H and F are always output to the PLC under acknowledge-
ment control.
For slow auxiliary function output (bits 0 to 3 = 0), the auxiliary function is not acknowledged
by the PLC until the cyclic user program (UB1) has been run once.
For fast auxiliary function output (bits 0 to 3 = 1), the auxiliary function is acknowledged by
the PLC already after the basic program has been run once. The auxiliary function can be
safely recognized in the PLC user program, but read-in disable, feed hold, etc. cannot take
effect in the same NC block.
Bit 0 to 3=1
Bit 0 to 3=0
Notes:
• The auxiliary functions M and H can be declared as fast auxiliary functions by
programming "–" (e.g. M-03) (see Programming Guide).
• If several auxiliary functions are programmed in one block, all auxiliary functions must be
parameterized as fast auxiliary functions so that output to the PLC is "fast". This also
applies to the F word even if it is not transferred to the PLC (see MD 544*, bit 0).
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SINUMERIK 840C (IA)
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Bit 0 = 0 Inhibits auxiliary function output to the PLC
Auxiliary functions are: M, S, T, H, D. Use is recommended for
computational channels.
For output of the programmed F value to the PLC, see NC MD 544*,
bit 0.
Active: In the next block
7 6
Fast auxiliary function output to the PLC
Slow auxiliary function output to the PLC (default setting).
Active: Immediately
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6 NC Machine Data (NC MD), NC Setting Data (NC SD)
6.6.3 Channel-specific MD bits 1 (channel bits)
Bit No.
5 4 3
Fast auxiliary function output to the PLC
T
6FC5197- AA50
2 1 0
S F D
6–137