Preventing on-line edits for a Safety PLC program

Hi All, Is there a better way to prevent (lock-up) on-line editing of a Safet PLC application program (designed to meet SIL2) other than the usual password
protection and RUN / REMOTE (Program) key?
Paul Bennett, Can you please respond to this query?
Can anyone tell me what protection features are offered for Safety PLCs such as QUADLOG, HIMA, FSC, TRICONNEX / TRIPLEX? Thanks in advance, Raj Sreenevasan
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Raj Sreenevasan wrote:

With the PLC equipment and programming terminal physically secured, the RUN/REMOTE key on may of the PLC's (such as Telemechanique, AB, GE Fanuc and Siemens) would be the most secure from in-advertent changes. In order that I understand your question thoroughly, do you wish to prevent persons with legitimate access to the equipment from editing the running code? That is certainly more difficult and I would need to know some more specifics about the system you have.
For SIL2 systems I usually go with embedded controllers in my own control system designs.

I'll have to look in my glossary of terms for that little snippet of alphabet soup. That is at the works office so it will be a little while before I get back to you on that (others in the meantime are free to assist).
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Paul E. Bennett ....................<email:// snipped-for-privacy@amleth.demon.co.uk>
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