Saving the Buffered Data of the %R Area
The buffered part of the %R area can be saved on the SD card and read from the card. This can be necessary, if, for example, the controller has to be replaced.
Copy the data from the %R area and write it to the CPU’s RAM disk as file
Save the file to the SD Card.
Load the file from the SD Card to the CPU’s RAM disk.
Copy the data from the RAM disk to the %R area.
Caution
Data mismatch can occur!
The variables structure / layout has to be identical to the old one and should not be changed!
Saving and reading the data can be done using Function Blocks in the user program or with the PLC Browser contained in the Automation_Builder. The Function Blocks are contained in the SysInt_AC500_V10.lib: Contents-Internal-System-Library
| Function | PLC Browser command | Function Block |
|---|---|---|
| Copy from %R area to RAM disk | persistent save | PERSISTENT_SAVE |
| Save file to SD Card | persistent export | PERSISTENT_EXPORT |
| Read file from SD Card to RAM disk | persistent import | PERSISTENT_IMPORT |
| Copy data from RAM disk to %R area | persistent restore | PERSISTENT_RESTORE |
| Delete buffered data of the PERSISTENT area | persistent clear | PERSISTENT_CLEAR |
Caution
:strong:Cycle consistency for data
If cycle consistency is required for the data, this has to be implemented in the user program. That means, that the data may not be changed during copying to/from the %R area from/to the RAM disk. If saving is done using the PLC Browser, this can be easily carried out by stopping the user program.
Caution
:strong:Cycle time for copying the PERSISTENT area
Copying the PERSISTENT area takes some milliseconds (see the following table). Thus, an according cycle time has to be set in the task configuration. Please note the remarks on the task configuration!
| Action | Time in ms | |||
|---|---|---|---|---|
CPU PM55x CPU PM56x |
CPU PM57x | CPU PM58x | CPU PM59x | |
| Restoring 1 kB (1024 bytes) | ||||
| PERSISTENT_CLEAR | <1 | <1 | <1 | <1 |
| PERSISTENT_SAVE | 2 | 2 | 2 | 2 |
| PERSISTENT_EXPORT | 900 | 1000 | 1000 | 500 |
| PERSISTENT_IMPORT | 100 | 500 | 1000 | 500 |
| PERSISTENT_RESTORE | 3 | 2 | <1 | 1 |
| Restoring 4 kB (4096 bytes) | ||||
| PERSISTENT_CLEAR | not possible | <1 | <1 | <1 |
| PERSISTENT_SAVE | not possible | 2 | 3 | 2 |
| PERSISTENT_EXPORT | not possible | 1000 | 1000 | 500 |
| PERSISTENT_IMPORT | not possible | 500 | 1000 | 500 |
| PERSISTENT_RESTORE | not possible | 3 | 3 | 2 |
| Restoring 64 kB (65536 bytes) | ||||
| PERSISTENT_CLEAR | not possible | not possible | 8 | 2 |
| PERSISTENT_SAVE | not possible | not possible | 11 | 6 |
| PERSISTENT_EXPORT | not possible | not possible | 2500 | 1000 |
| PERSISTENT_IMPORT | not possible | not possible | 2000 | 500 |
| PERSISTENT_RESTORE | not possible | not possible | 12 | 5 |
| Restoring max. PERSISTENT area | ||||
| 4 kB | 128 kB | 512 kB | ||
| PERSISTENT_CLEAR | <1 | <1 | 17 | 22 |
| PERSISTENT_SAVE | 2 | 2 | 22 | 35 |
| PERSISTENT_EXPORT | 900 | 1000 | 4000 | 8000 |
| PERSISTENT_IMPORT | 100 | 500 | 3000 | 4000 |
| PERSISTENT_RESTORE | 3 | 3 | 22 | 31 |