Auxiliary Functions Without Block Change Delay - Siemens SINUMERIK 840D sl Function Manual

H2: Auxiliary function outputs to PLC

8.10 Auxiliary functions without block change delay

● Transferred T, D and DL functions:
DB21, ... DBB116 - DBB136
● Transferred H and F functions:
DB21, ... DBB140 - DBB190
● Decoded M signals (M0 - M99):
DB21, ... DBB194 - DBB206 (dynamic M functions)
For information on the access procedure to the NC/PLC interface, see Section "P3: Basic PLC
program for SINUMERIK 840D sl (Page 821)".
A detailed description of the above data areas in the NC/PLC interface can be found in:
References:
List Manual, Lists, Book 2; PLC User Interfaces,
Section: Channel-specific signals (DB 21 - DB 30)"
8.10 Auxiliary functions without block change delay
Function
For auxiliary functions with parameterized and/or programmed output behavior, too:
● "Output duration one OB40 cycle (quick acknowledgment)"
● "Output before the motion" or "Output during the motion"
there may be drops in velocity in continuos-path mode (short traverse paths and high
velocities). This the system has to wait for acknowledgment of the auxiliary function by the
PLC toward the end of the block. To avoid these velocity drops, the block change can be made
irrespective of whether such auxiliary functions have been acknowledged:
Parameter assignment
Suppression of the block change delay with quick auxiliary functions is set via the machine
data:
MD22100 $MC_AUXFU_QUICK_BLOCKCHANGE (block change delay with quick auxiliary
functions)
Value
0
1
Boundary conditions
Synchronism of auxiliary functions that are output without a block change delay is no longer
ensured for the part program block in which they are programmed. In the worst case scenario,
acknowledgment comes one OB40 cycle and execution of the auxiliary function comes one
OB1 cycle after the change to the next part program block.
416
Meaning
In the case of quick auxiliary function output to the PLC, the block change is delayed until
acknowledgment by the PLC (OB40).
In the case of quick auxiliary function output to the PLC, the block change is not delayed.
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions