Unterschiede

Hier werden die Unterschiede zwischen zwei Versionen angezeigt.

--- embedded_systems:ethercat:start [2022-03-29 11:36] – Urs Graf
+++ embedded_systems:ethercat:start [2024-01-25 11:22] – Urs Graf
@@ Zeile 35: / Zeile 35: @@
   * Acyclic messages, so-called SDOs (service data objects), are not discussed in this documentation.
-At its lowest level, ethercat uses an ethernet frame to send EtherCAT datagrams containing commands to read or write data, or both ('r', 'w', 'rw'). Each Datagram consists of a header, its data and the **working counter**, which servers as a status indicator or checksum. Depending on the operation, the counter is either not incremented at all (+0), by 1, 2 or 3, if data was read, written or both. (TODO: which is read and which is write?)
+At its lowest level, ethercat uses an ethernet frame to send EtherCAT datagrams containing commands to read or write data, or both ('r', 'w', 'rw'). Each Datagram consists of a header, its data and the **working counter**, which servers as a status indicator or checksum. Depending on the operation, the counter is either not incremented at all (+0), by 1, 2 or 3, if data was read, written or both.
 The data that is actually read or written is accessed using a 4Gbit address space using byte.bit addressing. EtherCAT technically bit alignment, though in practice most  things seem to be byte aligned. This address space is called the **Process Data Image** or **PDI**.

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