Saia-Burgess Controls AG
Manual
Manual PCD 1 / PCD 2 Series
│ Document 26
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737 E
N22 │ 2013-11-26
CPUs and expansion housings
3-50
Backup of the user program
3
3.17.4 Backup/restore of RAM texts/DBs at run-time
As described above, the application can be copied to the flash card after
downloading. In order to store process data gathered during operation, there is a
facility to copy texts or DBs from extension memory (address >= 4000) to the flash
card, or conversely, to copy the last state written to the flash card back in the text/DB
in extension memory. A maximum of 64 Kbytes are available for this.
In order to use this function, the option shown below must be activated in the hard
-
ware configuration and the configuration must be loaded into the controller.
This leaves only 896 Kbytes available for the whole application (code, texts/DBs and
extension memory).
For storing texts/DBs on the flash card, restoring, deleting and running diagnostics,
there are four SYSRD/SYSWR instructions provided, as described in detail below;
these can be invoked at a suitable place in the user program. These instructions must
be used with great care, to prevent any damage to the unit or the flash card.