Skip to Content

SiePortal

The integrated platform for your product selection, buying and support workflow - bringing together Industry Mall and Online Support.

SiePortalDeutsch

Search

Home
Support Support
{{(apiData.Support | filter:{'rank':1}:true)[0].title}} Support
- Menu temporary not available
- Menu temporary not available
- Menue temporary not available
- {{item.title}}

Products & Services
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Support Support
{{(apiData.Support | filter:{'rank':1}:true)[0].title}} Support
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
MySiePortal MySiePortal
{{(apiData.MySiePortal | filter:{'rank':1}:true)[0].title}} MySiePortal
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Cart ({{apiData.CartCount}})

Navigation

WLAN W774-W734 thru R-Coax - Comm problems

Created by: lman80 at: 7/13/2014 7:02 PM (9 Replies)

Rating (1)

Thanks 2

10 Entries

7/13/2014 7:02 PM	Rate (0)
lman80 Member Joined: 7/13/2014 Last visit: 2/24/2022 Posts: 4 Rating: (0)	Hello. I have problems to setup my wireless comm between my AP 774 and CL 734. These are my WLAN system features: 70m R-Coax and helix antenna 5GHz. Only one client and one AP in this WLAN, we have a second WLAN in the same system but this one is working fine. The system is working, the comm is established but not stable, the comm is lost one or twice a day. I have bee received on-line support from SIEMENS but it has been almost two months and we have not been enable to fix it. As Siemens recomendation, as we have safety PLC, we install Key-plugs to enable IPCF to have a better performance, but instead, with the IPCF defautls configuration, the performance was much worse. We made changes with the configuration we had before, leaving IPCF enable and leaving only the 12MBBs rate. After this the comm improved but still having loss of communciation events, these are the faults logged: - At the AP: Too many retries - At the CL:Disassociated from AP 00:1b:1b:92:c8:3c with reason (No poll request from AP) Any idea what could be the problem?, is there something I can fix in configuration. i have tryed many changes, different channels, HW retries,security WEP... we have reviewed the installation and seems to be OK.The signal strength is also OK. Please any advice would be appreciated. Thanks

Suggestion To thank Quote Answer

7/17/2014 1:29 PM	Rate (0)
Fafner Silver Member Joined: 3/20/2013 Last visit: 3/11/2025 Posts: 676 Rating: (44)	Hey, only some things to try: you are already using WLAN mode 11a instead of 11n? you were setting the slower communication beyond 12MBs also? (as you are saying 12MBs, i guess you already have 11a) can you post you signal trace over the RCoax segment? (with telnet and the command "wlan signal-recorder wlan 0/1 100 20000 start" the recording starts (20 000 samples, 1 every 100 ms. afterwards you can download it in the WBM)
	Best Regards, Fafner
Suggestion To thank Quote Answer

7/17/2014 5:35 PM	Rate (0)
lman80 Member Joined: 7/13/2014 Last visit: 2/24/2022 Posts: 4 Rating: (0)	Hello Fafner, Yes, the system is already in the standar a since show a better performance than the n. Attahced you will find the recording, I. The signal strenght seems to e OK. Attachment signal_recorder_SCALANCE_W700_bajando.zip (284 Downloads)

Suggestion To thank Quote Answer

7/18/2014 7:11 AM	Rate (0)
Fafner Silver Member Joined: 3/20/2013 Last visit: 3/11/2025 Posts: 676 Rating: (44)	What is about your network behind the AP? Which update rate do you have? How many byte are to be send from AP to client in one second? How big is the broadcast/multicast load in your network?
	Best Regards, Fafner
Suggestion To thank Quote Answer

7/18/2014 7:12 AM	Rate (0)
Fafner Silver Member Joined: 3/20/2013 Last visit: 3/11/2025 Posts: 676 Rating: (44)	P.S. Indeed: the signal trace looks good
	Best Regards, Fafner
Suggestion To thank Quote Answer

7/19/2014 12:08 PM	Rate (1)
jklm Platinum Member Joined: 12/22/2006 Last visit: 1/25/2022 Posts: 1742 Rating: (309)	Hello, According to the signal trace, it seems that the speed is not reduced to 12 MBps. I would do this. A slower rate means a less complex modulation (which in turn means a more reliabel transmission and less repetitions). I understood that you now run without iPCF, and that you have only one AP (no roaming required). In this specific context, I would set the "background scan mode"in the client on "disabled". And also restrict the client to the radio channel used by the AP ("use allowed channels only" in thetab "allowed channel".This wil bind the client more strongly to the AP (it will not searchfor another AP with a better signal every 5 sec as per default). If the automation network is connected with the overal network, I also agree with Fafner that you should check how many broadcasts/multicats comming from the rest of the network impacts the wireless connection. You could consider to protect the automation network with a small router/firewall like Scalance S602. Routers will not passbroadcasts between subnets. If you are working with a decentralized I/O behind the wireless client, the PNIO update cycletime of it must be set to values compatible with a wireless Rcoax transmission (which never runs as fast as a wired connection). By default Step7 uses 2 msec in HWconfig. With one client, increase it to 16 msec. Also for the failsafe part, the profisafe monitoring times of the decentralized I/O (see in HWconfig), and also for the Timeout times at the blocksF_SEND(DP or S7) if they are used, must be compatible with a wireless Rcoax transmission. There is a table (S7fcotib as XLS sheet) allowing to compute the recommended minimum times. http://support.automation.siemens.com/WW/view/en/25412441
	Last edited by: jklm at: 7/19/2014 12:29 PM link to S7fcotib Best regards jklm Suggestion was helpful? Feel free to rate it.
Suggestion To thank Quote Answer

7/19/2014 3:25 PM	Rate (0)
lman80 Member Joined: 7/13/2014 Last visit: 2/24/2022 Posts: 4 Rating: (0)	Thank you Jklm and Fafner for your comments. here are the answers to your sugestions: - We have no newtwork behind our system, our network is independent. - Regading the Profinet uodate time, it was already changed for the remotes that go thru WLAN, this time was considered to be at least 6x time the F-Monitoring time. Right now is 256ms, i changed after having 128ms. - WE already have channels backgroud disable. - We still have disbaled IPCF sincewe have a better performance. - we are using only one channel, and the test with enable only the rate 12mbbs was already performed. - All the previous mentiones configurations were tested and still having comm drop outs. We are thinking about the main problem are interferences, since the R-Coax is 80m in vertical, at that height we have basicaly all the 5Ghz channels occupied. any other comment would be appreciated. Regards

Suggestion To thank Quote Answer

7/21/2014 7:22 AM	Rate (0)
Fafner Silver Member Joined: 3/20/2013 Last visit: 3/11/2025 Posts: 676 Rating: (44)	please have a look in your Access Points: Information -> WLAN -> Overlapping AP Are there entries?
	Best Regards, Fafner
Suggestion To thank Quote Answer

7/24/2014 3:56 PM	Rate (0)
lman80 Member Joined: 7/13/2014 Last visit: 2/24/2022 Posts: 4 Rating: (0)	I have indeed seen some Overlaps, but not in all channels, however we have done a spectrum analysis and found aut that almost all the channels are occupied. we selected the only one available and now we have no more comunication drop outs. at the end the problem was interfrence in the other channels

Suggestion To thank Quote Answer
This contribution was helpful to 2 thankful Users S_Moderator Fafner

8/6/2014 10:47 AM	Rate (0)
Fafner Silver Member Joined: 3/20/2013 Last visit: 3/11/2025 Posts: 676 Rating: (44)	Thanks for reporting your solution.
	Best Regards, Fafner
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on