SERCOS III V1.1.2 - 2 - Date 31.03.2009
Communication V1.1.2.1.7
1 History..................................................................................................................................... 3
2 Glossary................................................................................................................................... 5
3 Physical layer ........................................................................................................................ 13
4 Data link layer - Service specification .................................................................................. 13
4.1 Data Link services and concepts .................................................................................... 13
4.2 Service channel services (SVC services) ....................................................................... 14
4.2.1 Read (RD) ............................................................................................................... 14
4.2.2 Write (WR).............................................................................................................. 15
4.3 Hot-plug services............................................................................................................ 16
4.3.1 enable_hotplug (EHP) ............................................................................................. 16
4.3.2 notify_hotplug (NHP) ............................................................................................. 16
4.4 RTC services .................................................................................................................. 17
4.4.1 initiate_cyclic_communication (ICC)
..................................................................... 17
4.4.2 notify_cyclic_communication (NCC)
..................................................................... 18
4.4.3 disable_cyclic_communication (DCC) ................................................................... 18
4.4.4 notify_error (NER).................................................................................................. 19
4.4.5 notify_cyclic_communication_disabled (NCCD)................................................... 19
4.4.6 notify_cyclic_data (NCD) ....................................................................................... 19
4.4.7 read_cyclic (RDC)................................................................................................... 19
4.4.8 write_cyclic (WRC) ................................................................................................ 20
4.4.9 get_network_status (GNS) ...................................................................................... 20
4.4.10 get_device_status (GDS)....................................................................................... 21
4.4.11 set_device_status (SDS)........................................................................................ 21
4.4.12 notify_network_status_change (NNSC) ............................................................... 22
4.4.13 notify_device_status_change (NDSC) .................................................................. 22
5 Data link layer - Protocol specification................................................................................. 23
5.1 Overview ........................................................................................................................ 23
5.2 DLPDU structure............................................................................................................ 25
5.2.1 General DLPDU identification................................................................................ 25
5.2.2 General DLPDU structure....................................................................................... 25
5.2.3 DLPDU header details ............................................................................................ 26
5.2.4 MDT DLPDU
.......................................................................................................... 28
5.2.5 AT DLPDU ............................................................................................................. 51
5.3 DL management
............................................................................................................. 67
5.3.1 Overview ................................................................................................................. 67
5.3.2 Enable and disable cyclic communication .............................................................. 67
5.3.3 Hot-plug procedure
................................................................................................. 77
5.4 Data transmission methods
............................................................................................. 81
5.4.1 Overview ................................................................................................................. 81
5.4.2 Service channel (SVC) ............................................................................................ 81
5.4.3 RT Channel ........................................................................................................... 100
5.4.4 Multiplexing of real-time data with data containers ............................................. 100
5.5 Telegram timing and DLPDU handling....................................................................... 115
5.5.1 Usage of real-time channel with different network topologies ............................. 115
5.5.2 Communication mechanisms ................................................................................ 116
5.5.3 Synchronization..................................................................................................... 130
5.6 Communication error handling and monitoring
........................................................... 134
5.6.1 Invalid telegrams
................................................................................................... 134
5.6.2 Response to MDT and AT telegram failure.......................................................... 135
5.6.3 Error counters in the master and the slave ............................................................ 135
5.6.4 Error effects on communication phases ................................................................ 135