Chapter 4. CPU Operation164 PACSystems* RX7i, RX3i and RSTi-EP CPU Reference Manual GFK-2222AD4.9.2 OEM Protection – Legacy ModeOriginal Equipment Manufacturer (OEM) protection provides a higher level of security than passwordlevels 1 through 4. This feature allows a third-party OEM to create control programs for the CPU and thenset the OEM-locked mode, which prevents the end user from reading or modifying the program.The OEM protection feature is enabled/disabled using a 1- to 7-character password, known as the OEMkey. When OEM protection is enabled, all read and write access to the CPU program and configuration isprohibited: any store, load, verify, or clear user program operation will fail.OEM Protection in Systems that Load from Flash MemoryFor OEM protection, it is recommended to store the program to User Flash and set configuration toalways load from Flash. When setting up OEM protection it is important to download the user programto RAM and User Flash before enabling the OEM protection. For example, the following steps can be usedto set up OEM protection.1. Set OEM Key password (Must be at Access Level 4 to set OEM Key)2. Download program to both RAM and User Flash.3. Set OEM Protection to the Locked state (see firmware note below).If you are storing a non-blank OEM key to flash memory, you should be careful to record the OEM key forfuture reference. If disabling OEM protection, be sure to clear the OEM key that is stored in flash memory.Note: In CPU firmware versions 7.80 or later which support Enhanced Security (with mergedpassword tables), OEM Protection Lock must be explicitly set.In earlier versions, the OEM Protection could be enabled in User Flash without explicitly settingthe OEM Protection to Locked. With the earlier firmware, a non-blank OEM Key that is loadedfrom User Flash at power-up would result in an automatic OEM Lock. In CPU firmware versions7.80 or later (i.e. with merged passwords), this is no longer supported.In firmware versions earlier than 6.01, the OEM protection was not preserved unless a batterywas attached.
