Infoportal
Unterschiede
Hier werden die Unterschiede zwischen zwei Versionen angezeigt.
| Nächste ÜberarbeitungBeide Seiten der Revision | |||
| embedded_systems:ethercat:choose_linux_master [2019-01-08 17:09] – angelegt mgehrig2 | embedded_systems:ethercat:choose_linux_master [2019-02-08 14:33] – mgehrig2 | ||
|---|---|---|---|
| Zeile 1: | Zeile 1: | ||
| ====== Choose a Linux Master ====== | ====== Choose a Linux Master ====== | ||
| + | ===== Realtime capability ===== | ||
| + | Depending on the requirements, | ||
| + | Very good real-time behavior (max. jitter < 30 usec) is required if: | ||
| + | * The Linux master must set the clock. E.g. if no distributed clock is used and the bus cannot be synchronized with a slave. See [[embedded_systems: | ||
| + | A time buffer, which is larger than the largest expected jitter, has to be used. | ||
| + | If the time buffer is smaller, then in some cases the timing cannot be met and the data from this cycle is lost. | ||
| + | |||
| + | The smaller this time buffer is, the more time is available for calculations on the master. | ||
| + | However, the buffer must be large enough so that the system can reliably meet the timing deadlines. | ||
| + | A good real-time behavior enables a smaller time buffer. | ||
| + | |||
| + | The minimum cycletime, and thus also the maximum frequency of the control loop, is mainly given by this time buffer plus the calculation time (EEROS). | ||
| + | |||
| + | TODO graphic time management on master | ||
| + | |||
| + | See [[software: | ||
| + | |||
| + | [[software: | ||
| + | There are also some tips on how to find a PC with good real-time performance. | ||