Siemens SINUMERIK 840D sl Commissioning Manual page 60

PLC commissioning
5.2 Creating a SIMATIC S7 project (PROFIBUS)
5. Click "Options" and then the "Isochronous mode" tab.
6. To enable reproducible access to peripherals (for handwheel mode), the PROFIBUS DP
must have a constant bus cycle time. The following entries are necessary under
Isochronous mode:
– Click the "Activate isochronous bus cycle" field.
– Enter the cycle, e.g. "2 ms" for the "Equidistant DP cycle" for the integrated PROFIBUS
– Click the "Times Ti and To equal for all slaves" field.
– The fields "Time Ti" and "Time To" must contain a value "< 2 ms".
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(also see: MD10050 $MN_SYSCLOCK_CYCLE_TIME).
CNC Commissioning: NC, PLC, Drive
Commissioning Manual, 12/2019, A5E48312804B AA