Siemens SIMATIC ET 200M Operating Instructions Manual page 172

Functions
8.6 Isochrone mode
Optimizing the equidistant time
● An optimization of the periods for the equidistant bus cycle can be achieved through the
● The greatest delay (configurable) with the digital input / output modules essentially
● The smaller the input delays are that you set for the digital input modules, the shorter the
● In the case of modules which support clock synchronism, the processing time at the
● The achievable, minimum equidistant time in the station depends on the number of
● The equidistance time is reduced if you increase the transmission rate.
170
correct plugging sequence of the I/O modules:
– Plug the output modules with the longest processing time on the left in the ET 200M.
– Plug the input modules with the longest processing time on the right in the ET 200M.
Detailed information can be found in the technical data for the module concerned.
determines the length of the equidistant DP cycle.
Tip: In isochrone mode, ensure the same delay on all digital modules in the ET 200M
station.
possible equidistance times will be.
Tip: If possible, for the digital input modules set an input delay of 0.1 ms.
module must also be taken into consideration.
modules in the ET 200M.
You can also achieve small equidistance times if you distribute the modules of an ET
200M (with a large number of modules) between two ET 200M stations.
Tip: Set the greatest possible Baud rate.
Operating Instructions, 12/2008, EWA-4NEB780600602-08
ET 200M