Auxiliary Functions Without Block Change Delay - Siemens SINUMERIK 828D Function Manual

H2: Auxiliary function outputs to PLC

8.10 Auxiliary functions without block change delay

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 Meaning
0 In the case of quick auxiliary function output to the PLC, the block change is delayed until
acknowledgment by the PLC (OB40).
1 In the case of quick auxiliary function output to the PLC, the block change is not delayed.
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.
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Function Manual, 09/2011, 6FC5397-0BP40-2BA0
Basic Functions