Hardware Manual

Hardware Manual PCD 1 / PCD 2 Series│Document 26 / 737│Edition EN 15│2008-07-22

Saia-Burgess Controls AG

Backup of the user program

CPUs and expansion housings

3

3.15.4 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.