System behavior when writing persistent data
|
Write trigger |
Internal optimization of persistent data access |
Persistent data consistency |
Plc cycle time exceedance |
|---|---|---|---|
|
Function block WritePersistentData |
None |
All data is from same plc cycle. |
Yes, if writing of all data takes more than plc cycle time. |
|
Function block FB_WritePersistentData and SPDM_2PASS |
Yes |
All data is from same plc cycle. |
Yes, if writing of all data takes more than plc cycle time. |
|
Function block FB_WritePersistentData and SPDM_VAR_BOOST |
Yes |
The data of each variable is from same plc cycle. |
Rare, if writing of biggest pers. variable takes more than plc cycle time. |
|
TwinCAT system stop (all persistent data is written automatically on TwinCAT system stop). |
Yes |
All data is from same plc cycle. |
None |