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How to configure AO module on SIL2 certified system

Created by: hari123 at: 5/10/2011 1:51 PM (6 Replies)

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5/10/2011 1:51 PM	Rate (0)
hari123 Posts: 8 Rating: (0)	Dear all, We are working on a project using SIL 2 certified system. We have currently configured DI & DO on this system. But I also need to configure AO module on SIL 2 system. So,does anybody have any sugguestion on how I can configure AO module on SIL 2 certified system. Waiting for ur reply. Thank you
hari123 Posts: 8 Rating: (0)
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5/10/2011 3:23 PM	Rate (0)
Silent Bob Posts: 836 Rating: (100)	Hi, there are several failsafe-AO modules for ET200s. Have you had a look in the manual "S7 F - Safety Engineering in SIMATIC S7"?
Silent Bob Posts: 836 Rating: (100)
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5/12/2011 7:01 AM	Rate (0)
hari123 Posts: 8 Rating: (0)	Hi Silent Bob, Thanks for the reply. I Checked the Manual as u referred,but it doesnt have any info about configuring AO modules for the SIL 2 certified system. Is there any other way to find out the solution?
hari123 Posts: 8 Rating: (0)
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5/16/2011 10:51 AM	Rate (3)
H-H Platinum Member Joined: 7/2/2008 Last visit: 9/30/2024 Posts: 928 Rating: (309)	Dear hari123 , I'm afraid it's not possible to configure AQ SIL2. This is conceptually wrong. A SIL2 is a grade for an SIS (Safety Instrumented System) which is required to driveyour plant to a safe state and consequently it doesn't require any analog outputs. So, the analog outputs are used only in process control which doesn't require a SIL grade. If you need this analog output for process control then you can use standard analog output module and configure it normally in the CPU that contains the F-Program and still your SIS system is SIL2 but only one CPU is used for SIS and PCS. Frankly speaking, some vendors other than Siemens do have SIL2 analog output modules for a very tight purpose called partial stroke testing. So, every know and then the module changes the position of the valve very slightly to make sure that valve is responding well. But still the final element (valve) has only 2 states, open or close not regulating. Best regards. H-H

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This contribution was helpful to 6 thankful Users fritz dchartier Phantom75 Ayman Elotaify Yoga Shankar S7 AUTOMAN

5/21/2011 10:14 PM	Rate (1)
ABN Posts: 212 Rating: (12)	Hi, Thanks H-H for detailed information One can use the manual "Automation system Fail-safe signal modules" available on site. this manual in detail explains the Wiring philosophy requried for SIL2 and SIL 3 concepts for DI/DO and AI.
ABN Posts: 212 Rating: (12)
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6/3/2011 4:40 PM	Rate (0)
fanlfc Posts: 13 Rating: (1)	Information provided by H-H is very helpful, also as mentioned by H-H to drive the plant in the safe state we don't need Analog outputs. According to me same is the reason we don't have any fail safe AO modules in our ET-200M series.
fanlfc Posts: 13 Rating: (1)
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This contribution was helpful to 1 thankful Users H-H

6/5/2011 9:37 AM	Rate (0)
Krish Silver Member Joined: 5/24/2007 Last visit: 4/24/2024 Posts: 284 Rating: (27)	Hi Hari123 As far as I know you cannot have a single SIL2 Certified analog output. Normally the process is failsafe open ,failsafe close or failsafe stayput which you can realise by choosing correct type of valves ,positioners and additionally Fail Safe DO. In case the process requires that you have to controlalso in failure mode this has to be implementedwith a double (redundant) control lines ( that is the only you can have regulated outputs even with one failure in the safety cycle. That is the reason whyyou do not getFailsafe AOs in the market. Maybe you should go over your safety analysis once again to see what is to be done. In caseyou need some idea onhow to realisesuch safety function , you could comeback to the forum. Many would be willing to help Krish

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