Is it possible to meet SIL requirements using OPC?


Thread Starter


I am involved in a SIL2 Software project. Relevant data has to be transmitted from an HMI computer to the main control application using OPC. Is it possible to meet safety requirements using OPC?

Sorry if the question seems to be absurd but I am new to this subject.

Thanks in advance.

Hello Chiv
I'm also involved in using OPC versus HIMA (PLC) in a Honeywell application. The plant has several SIL 2 + 3 scenarios guarded by several HIMA PLC applications.

HIMA recieves directly the signals from the transmitters in the field. Then HIMA checks if the signal is out of range and respond according the SIL protocol immidiately if this is the case.
OPC however is the link between HIMA PLC and the Honeywell HMI. If OPC or Honeywell are shutting down the operator has no information from the proces. That's concerning but if the PLC is still working the safeguarding is still intact.

So in my opinion, if the PLC recieves and progresses directly the signals from the field, OPC has no influence on the safety requirements.

Please correct me if i'm wrong.


Hi Chev,

The SIL standards will not be voided if the OPC interface is only being used for monitoring the values that are being read by the HEMA PLC. If the ESD logic requires any information from the Honeywell system that is necessary for the ESD logic to proceed, then you are violating the SIL standards.

If you are only monitoring through Honeywell, then don't worry. If you are reading any critical values, then you need to bring these signals in physical, Hard Wired form to the Hema PLC.

Hope this helps.

Abhijit Goswami, Haldia

Governing standard IEC 61511 has laid down specific requirements on application, utility and embedded software used in safety applications.

You need to review your software architecture in reference to your designed safety requirement specification and if you can conclude that the OPC interface is not a part of it, probably no further evaluation is required.

Section 12 of IEC61511-1 is your reference for next course of action.