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write on internal parameter in SIS

dear friends,

i'd like to write a code on SIS which force some parameters on SIS to true/false simultaneously via visual basic. how can i do this? i use "frssecurewrite", but with this function, i can just force in one parameter!

• securewrite
• write parameter
• internal parameter

semova2

• 21 Nov 2017 10:32 AM
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2 Replies

• Andre Dicaire

  

  • 22 Nov 2017 10:27 PM

  The FRSSecurewrite for SIS applies a validation step, and is not intended for programmatic writes. This is an SIS system, right?
  
  But DeltaV SIS is often used for more than IEC61511 Safety instrumented functions. Not knowing what this application is, we have no way of knowing what would an appropriate solution.
  
  The SIF can read data from the BPCS, and in that way, can validate whether any action should be taken based on the value. The BPCS can also read values from the SIS.
  
  So, if you want to manipulate several parameters in a SIF, you can write this logic in the SIF, and then trigger it from the BPCS. You could manually do a Secure Write to trigger the logic, thus with a single parameter write, the SIF would take care of executing the simultaneouls manipulation.
  
  If the multiple variables to be forced are in different SIF's, you could elevate a secure parameter in a SIF, and all SIFs would read this secure parameter to affect their local parameters.
  
  IF you create a BPCS parameter which the SIF then reads, you can use a standard FRS write to set this value, and let the SIF's read and act on the value.
  
  Since the SIS in intended to be independent and provides a separate level of protection, the BPCS is purposefully blocked from programmatic writes into the logic solver. Otherwise, some one could deploy a BPCS module that inappropriately affects the safety functions.

  Andre Dicaire

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• semova2

  

  • 25 Nov 2017 6:57 AM

  In reply to Andre Dicaire:

  dear Andre,
  thanks for your answer. that's you said is right. i put a parameter in HMI graphic display which change internal read parameter in SIS.
  but there is a problem. when you want to change the parameter (by frssecurewrite), if you need to change other related parameters in this code, just one parameter will change, not more!
  what do you think what the problem is?

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