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Distributed fail safe I/O

Created by: Aden at: 2/13/2010 4:58 PM (5 Replies)

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2/13/2010 4:58 PM	Rate (0)
Aden Regular Member Joined: 2/8/2010 Last visit: 6/27/2024 Posts: 53 Rating: (1)	Hello, is it possible to have ET200M station with fail safe I/O and standard S7-300 CPU? For what pusprose such combination can be used? For example, for safety critical application S7-300F is used which includes F CPU and F I/O SM modules. But is it to possible to have such application that needsonly F I/O and standard CPU? Thanks

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2/13/2010 8:55 PM	Rate (0)
Ayman Elotaify Platinum Expert Joined: 5/28/2008 Last visit: 9/9/2024 Posts: 4515 Rating: (839)	Aden Hello, is it possible to have ET200M station with fail safe I/O and standard S7-300 CPU? For what pusprose such combination can be used? For example, for safety critical application S7-300F is used which includes F CPU and F I/O SM modules. But is it to possible to have such application that needsonly F I/O and standard CPU? Thanks Dear Aden, Generally, Fail safe modules is made to be used with Fail Safe CPUs. You may use distributed safety CPUs like: CPU315F-2 DP, CPU315F-2 PN/DP, CPU317F-2 DP, CPU317F-2 PN/DP, CPU 319F-3 PN/DP or CPU 416F. And also you can use the Fail safe modules with Fault tollerent CPUs after purchasing F-Copy licence, F-System, CFC / Safety Matrix. And you should build your program using F-library. Now back again to your question: Aden Hello, But is it to possible to have such application that needsonly F I/O and standard CPU? Yes, you can use F-I/O modules with standard CPUs as standard modules. If you want to use them as Fail safe modules, you should have Fail safe CPU. Hope this helps
	Ayman Elotaify
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2/14/2010 8:20 AM	Rate (0)
Aden Regular Member Joined: 2/8/2010 Last visit: 6/27/2024 Posts: 53 Rating: (1)	Hi Ayman, from your reply I can conclude that distributed F I/Os don't make any sense if used with standard CPU. In that case they will behave same as standard SM modules. I know in general how fail safe CPU is working. Key things that provide fail safe functionality are code diversity and time redundancy. There is a separate memora area in fail safe CPU in which fail safe part of the program is executed. If this concept is true (and I think it is) then this opens a new question: Whatis the purpose of F I/O modules? If safety functions are processed in fail safe CPU, what makes the difference between F I/Os and standard I/Os? Will fail safe functionality be kept if standard SM modules are used instead of F I/Os. Thanks

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2/14/2010 2:11 PM	Rate (0)
yy1 Gold Member Joined: 3/24/2009 Last visit: 7/9/2024 Posts: 535 Rating: (112)	Aden Will fail safe functionality be kept if standard SM modules are used instead of F I/Os. Dear Aden, to have the failsafe functionality you have to use both failsafe CPU and SM modules. They communicate using the PROFIsafe-protocol, so both parts are required. Best regards, yy1

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2/15/2010 11:22 AM	Rate (0)
Aden Regular Member Joined: 2/8/2010 Last visit: 6/27/2024 Posts: 53 Rating: (1)	yy1, thank you for your reply. I can uderstand the concept in which allcomponents must be F in order whole system to be "F". That is natural to understand. I must admit I didn't know that Profisafe must be used too. However, what I don't know is what makesF modules different from standard modules (except yellow lablel and price). I can understand what makes difference between standard CPU abdFCPU since F CPU contains safety program area. What is the most important difference between F and standard SM modules? Now, I realized that I need to make much different equipment specification than originally planned. Is there ET200M fail safe station as well? THis fail safe concept is very hard to understand. Any case studies would help if there are any.... Thanks

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2/16/2010 7:51 AM	Rate (1)
yy1 Gold Member Joined: 3/24/2009 Last visit: 7/9/2024 Posts: 535 Rating: (112)	Dear Aden, well, I don't know all differeces between F and standard SM-modules, but as far as I understand the safety concept, the SM-modules are completely different. Have a look at this document. The major difference between fail-safe modules and standard ET 200 modules is that fail-safe modules have a two-channel internal design. Both integrated processors monitor each other and automatically test the input and output wiring, and place the F-module in a safe state in the event of a fault. The fail-safe controller communicates with the fail-safe module via the PROFIsafe safety-related bus profile. Fail-safe power modules supply load voltage to the potential group and safely shut down the load voltage for standard output modules. Fail-safe digital input modules record the signal states of safety-related sensors (e.g. emergency stop pushbutton) and send corresponding safety message frames to the fail-safe controller. Fail-safe digital output modules are suitable for switching processes with short-circuit monitoring up to the actuator. Hope this helps you. Best regards, yy1
	Last edited by: yy1 at: 2/16/2010 7:58 AM correct link-adress
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