1662 HEIDENHAIN Technical Manual iTNC 530 HSCI
Cycle times
PLC I/Os
Cycle times during reading and writing of PLC inputs/outputs
Compared with the hardware components in systems with MC 42x/CC 42x,
there are different cycle times during reading and writing of PLC inputs and
outputs with the new control system with HSCI. The differences result from
the changed communication of the individual components via HSCI and the
synchronization required during data transfer.
The procedures for these software versions are described in the following:
NC software iTNC 530: 606 42x-01
Or as of NC software iTNC 530: 606 42x-02
Overview of cycle
times
The flow chart shows a comparison of the HSCI system with the respective
software versions and a system with MC 42x/CC 42x. The decisive worst-
case cycle times for reading and writing as well as the typical run times for the
PLC cycle and the PLC program were used in the diagram:
Times in the flow chart:
1) Reading of PLC inputs
Time needed to read in the physical input states and transfer them to the
PLC memory (e.g. filter run times, hardware transmission paths). The
specified PLC cycle time passing until the input information is actually
processed by the PLC program must also be considered here.
• Worst case for HSCI SW 606 42x-01: 15.7 ms
• Best case for HSCI SW 606 42x-01: 10.5 ms
• Worst case for HSCI as of SW 606 42x-02: 9.7 ms
• Best case for HSCI as of SW 606 42x-02: 4.5 ms
• Worst case for MC 42x/CC42x: 5.0 ms
2) Run time of the PLC program
Along with the cycle times for reading and writing of PLC inputs and
outputs, the PLC run time must be considered. The typical run time of the
PLC program is up to 1.5 ms.
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