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WDS w/ iPCF

Created by: Jim Tabbert at: 8/24/2009 9:50 PM (13 Replies)

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8/24/2009 9:50 PM	Rate (0)
Jim Tabbert Posts: 3 Rating: (0)	Hey guys, I've spent a great deal of time looking for information and various architectures on WDS using iPCF. The application has a table that spins and uses a slip ring to pass communications and power to the table. The S7315PN/DP resides on the table and an MP277 10" along with an ET200S drop outside the slip ring. At this point all are on Ethernet/Profinet. My initial thought process is to replace the wired connection with a W788RR access point and W747RR client as a wire replacer. From what I've read, it's strongly advisable to use iPCF with Profinet I/O. I'm struggling trying to determine what the best course of action would be given that the HMI would reside on a client of it's own, or on the same client with the ET200S node.Alsothey're thedual channel versions of the W788 and W747, could that be an option? I've heard of seperating the RT I/O comms. from the HMI comms. each on there own channel. Any recommendations, case examples? Thanks in advance. Jim
Jim Tabbert Posts: 3 Rating: (0)
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8/24/2009 10:05 PM	Rate (0)
jklm Platinum Member Joined: 12/22/2006 Last visit: 1/25/2022 Posts: 1742 Rating: (309)	Hello, You don't need a WDS. You can put up to eight devices behind a W747 client, even with iPCF activated. For Profinet IO, the productive data is directly a MAC based communication. Therefore I would recommend to set in the WLAN ==> advanced settings, configure "L2T".
	Last edited by: edr at: 8/24/2009 10:07 PM Best regards jklm Suggestion was helpful? Feel free to rate it.
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8/25/2009 11:04 AM	Rate (0)
gcor Advanced Member Joined: 7/17/2008 Last visit: 10/25/2013 Posts: 34 Rating: (2)	Hey Jim, First of all you cannotuse WDS and iPDF at the same time in the same interface. Secondly if you buy a 788-2 take in account that only oneofits two interfaces could be configured with iPCF at the same time!!!! If you don't use "direct keys" in HMI, actually the HMI doesn't use Profinet, uses standard TCP/IP comm for his S7 links. If you use the L2T (layer 2 tunnel) in the Scalance W clientthat Eric metioned, you can connect up to 8 nodes to the client. Please read this FAQ: http://support.automation.siemens.com/WW/view/en/26562314 Some scenarios: http://support.automation.siemens.com/WW/view/en/31938420 Wich profinet update time do you need? Hope this info helps, anyway post any comment or doubt Regards

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8/26/2009 1:17 AM	Rate (0)
Jim Tabbert Posts: 3 Rating: (0)	Thanks, I'm starting to put this together. I'm still struggling with what my limitations are for incorporating the HMI. I've heardcommunications isslowed significantly when hanging an HMI off the same W747RR client module as the ET200S node, using iPCF.If I use a W788-2RR access point with one channel allocated to iPCF and the other not, would that intern require two seperate W747RR client modules? Onededicated for the ET200S node, and the other for the HMI. I'm trying toincorporate an HMI into the scheme using the fewest amount of hardware, yet maintainI/Othroughput times to no more than 100ms. I found the site below, under the "Profinet I/O" section, which allows one to configure a wireless based system and incorporate an HMI into the scheme. Unfortunately for me, it never places the HMI on the client side. Always on the AP side. I like the tool and it has me believing I can meet the time requirements I'm looking for but I still dont understand some of the results it displays. Please share if you know how to read the performance data results. https://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&lang=en&objid=25209605&caller=view Thank you for your help thus far, It's been very informative. Jim
Jim Tabbert Posts: 3 Rating: (0)
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8/26/2009 9:55 AM	Rate (0)
INS Gold Member Joined: 4/6/2006 Last visit: 2/5/2024 Posts: 604 Rating: (56)	Hi Jim, Normally PN IO should not be effected by the traffic generated by the Panel due to the priority mechanism in iPCF. This ensures that PN IO frames are handled with a higher priority then the 'normal' frames. the only thing you should think about is the speed and the number of traffic you want to send but if it's a SCADA for monitoring only this won't be a problem at all. Just use a Scalance W788-1RR or a Scalance W784-1RR and as a Client you could use a Scalance W747-1RR or Scalance W747-1. You also write about an update of 100 ms maxcimum this would mean you want to have a PN IO Update time of 32 ms and 3 retries am I correct? This is no problem as long as your signal strength doesn't go below the 60% and you do need a channel which is free of interferences from other Wireless devices. In most cases this means that you should use 5 GHz frequencies. But check the Country Approvals for the Scalance W devices before you need to choose a channel since not every contry has the same regulations. Certificates for WLAN
	Last edited by: INS at: 8/26/2009 11:40 AM Changed the first part. Best regards, INS
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8/26/2009 10:48 AM	Rate (0)
gcor Advanced Member Joined: 7/17/2008 Last visit: 10/25/2013 Posts: 34 Rating: (2)	Hi Jim, Hi INS, As far as I know Sclance W devices don't support 802.1p. They support 802.1q since they have VLANs, but 802.1p/d isn't mentioned in manual/operating instructions, so we can assume that they understand the 802.1q tagseven so theydon't have priority queues. Anyway, Jim, I complete agree with INS recommendation and warnings. That configuration should be enough. Good luck! Regards
	Last edited by: gcor at: 8/26/2009 10:49 AM
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8/26/2009 11:53 AM	Rate (0)
INS Gold Member Joined: 4/6/2006 Last visit: 2/5/2024 Posts: 604 Rating: (56)	Hi gcor, In basic Scalance W works with queues but not as I had written in my previous post because there I talked about the iPCF mechanism. I already edited it to have no wrong information in the forum. Inside the iPCF mechanism there is something which gives the PN IO Traffic a higher priority then other traffic. This mechanism is proprietary. Something is written in the manual. See the quote below. When should iPCF be used? iPCF can be recommended, in particular, when a high data throughput is required despite a large number of nodes or when extremely short handover times are required. With PNIO data traffic (ProfiNET IO), the iPCF mechanism was further optimized by handling PNIO traffic with high priority. And about the qeues you should check the WMM mechanism which is also known as the 802.11e which could explained as the WLAN version of 802.1p. And Scalance switches do support this with Standard WLAN, DCF. See a small quote from the manual below: With wireless multimedia, multimedia frames are transferred according to the IEEE 802.11e standard with a higher priority. Select the "Enable WMM" option if you want frames evaluated according to their priority and sent prioritized over the WLAN interface. I hope this correct my mistake, ;-)
	Best regards, INS
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This contribution was helpful to 1 thankful Users gcor

8/26/2009 12:41 PM	Rate (0)
gcor Advanced Member Joined: 7/17/2008 Last visit: 10/25/2013 Posts: 34 Rating: (2)	Perfect! Yes, I heard something about this special-propietary-PNIO-priorization, but a log or stats about this functionality would be really useful..... maybe there is a hidden-special-propiatary menu... Regards

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8/26/2009 1:08 PM	Rate (0)
INS Gold Member Joined: 4/6/2006 Last visit: 2/5/2024 Posts: 604 Rating: (56)	Hi gcor, I'm not sure what you mean with your last reaction and about the special menu. As soon as you enable the PN IO Option in the iPCF menu you have this feature enabled according to the manual. So nothing more is needed in my opinion.
	Best regards, INS
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8/26/2009 1:19 PM	Rate (0)
gcor Advanced Member Joined: 7/17/2008 Last visit: 10/25/2013 Posts: 34 Rating: (2)	Hi INS, Sorry I didn't express myself. I know how to configure it, but actually we don't know how exactly that PNIO priorization (and iPCF itself) works . So I speculatedabout the existenceof a hidden option ( in CLI ) or whichever in order to control this not-completely-clear functionalities Have a nice day! Regards

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