wls connection reliability issue

[rezaravani]

Dear Corby,

Thanks you very much! I have lots of experience with NI devices but this is my first time experience with WSN devices from NI, Actually we are using 10 units of WLS-9206 for our data acquisition purpose. Anyway VI you have attached is great and solved my problem. 

By the way I have found another solution in below link from NI:

http://zone.ni.com/devzone/cda/epd/p/id/6172

It can work correctly (I mean disconnecting and connecting the device can not effect on its continues work) just in Finite sampling mode , but when changed it to continuos sample  mode then the problem still exists. Do you know the reason?

Thanks again from NI support and specially you. 

[Corby_B]

Hello rezaravani,

Thanks for your post back!

Glad to hear that the example I posted was able to get you up and running. 

The reason that you don't see the error in finite mode is because once you make it to the read function the hardware or WLS-9206 has already collected the data and stored it on its internal memory. So now all that has to happen is to transfer the data of TCP/IP to the host computer. Its not so limited on time to transfer because its a finite task. Now when we talk about continuous its a bit different because we are streaming data from the WLS-9206. If we have a network interruption then we can't guarantee that network can recover fast enough to not over flow the buffer (FIFO) on the WLS-9206. Let me know if this helps!

By the way were you able to upgrade the firmware on your 10 WLS-9206s. You will notice some improved performance if you are in harsh wireless environments.

Cheers!

Corby Bryan

NIC AE-Specialist

www.ni.com/support

[rezaravani]

Dear Corby,

Sorry for my late update! Actually We were on site to test and finalize our data acquisition program, thanks for your last help and the VI you sent me. 

About updating the firmware of WLS9206, where can I find it? 

Another issue, one of our WLS card prompts me this error, I can find it through MAX but when I want to add it, the below message appears, please refer to attached file.

Thanks again for your attention and assistance.

/Reza. 

[Corby_B]

Hello Reza!

Thanks for your post back. 

The new 2.0.0 firmware can be found here and can be updated from MAX (Measurement and Automation Explorer). The firmware is for the WLS-9163 carrier so you can have any C-series module from this list in the carrier to update the firmware. The C-series module that is inserted into the 9163 will not be changed in any way by the firmware update. 

The error message you are seeing is a result of no C-series module being in the WLS-9163 carrier. To add this device to max it must have a C-series module in it to be configured and used. The C-series device that is in the WLS-9163 must be a supported C-series module in this list.

Let me know if this helps you solve any configuration issue you are having.

Have a great day!

Cheers

Corby Bryan

NIC AE-Specialist

www.ni.com/support

[Mikko_Tepponen]

Hi everyone,

We are facing connectivity issues with WLS-9163. Latest firmware installed, but the device seems to keep losing WLAN connectivity to AP. AP's used are Cisco Aironet..

In our environment only encrypted data can be sent but we haven't been able to get any encryption mode working. The problem goes as this:

1) WLS-9163 is configured to a SSID that uses e.g. WPA-PSK

2) Connection to AP is made

3) After a while connection drops (as noted by the WLS Link led not being active anymore)

If we look at the AP log we get following:

 *Aug 03 11:24:36.387: 00:80:92:41:6c:08 EAPOL Key message with invalid
               authenticator replay counter

The functionality is similar with other encryption methods, although WPA-PSK has been noted to function the best. If connected through ethernet, the device works fine.

Any suggestion on how to debug this?

Best Regards,

-Mikko-

[rezaravani]

Hi Mikko,

Actually I have some experiences with WLS9506 but I think yours should be the same regarding wireless part not DAQ part. I found they are so sensitive to their environtment and also AP. So make sure your env. is not noisy, your card is in the coverage of AP and if possible try another AP brands.

Good Luck!

Reza Ravani.

[Corby_B]

Hello Miikko,

Here are a couple of links the might also be helpful.

Make sure you have upgraded to the latest firmware for the WLS-9163. There have been some really significant improvements for "dirty" wireless environments.

http://joule.ni.com/nidu/cds/view/p/id/1615/lang/en

Also, check to see what other wireless networks are around you. This way you can choose a wireless channel that is not being used or over utilized. Its a free software called "inSSIDer".You just have to have a wireless card in your computer to use it.

http://www.metageek.net/products/inssider

Here is some useful information about using wireless daq

http://decibel.ni.com/content/docs/DOC-11073

Let us know if this helps!

Cheers

Corby

[Mikko_Tepponen]

Thanks Corby,

We have the latest firmware upgraded to the devices, but still experiencing issues. As our networks do lie in noisy environments and the AP's have to set on public use channels we are in bit of a bind here.

As a feedback I would suggest that you continue your R&D efforts on the radio access layer because as of such the devces are not much of use. 😞 I can understand the need of "clean channels" if you are polling an analog measurement multiple times per second, but if you are reading DI (like we are) every 30 sec. you should be able to do this even on noisy channels. If I'm going to need to put in a separate WLAN-ethernet transformer, I might as well use something like a MOXA device. Our test AP is of limited use and still we are experiencing issues on the radio path + we are using telco-grade AP's (Cisco & Alcatel) instead of cheap consumer models.

Best Regards,

-Mikko-

[Corby_B]

Hello Mikko,

Thanks for your response and we always appreciate any feedback that customers like you give. As always, we are in the process of working on new wireless products and the advancements that are being achieved are very significant.

Can you elaborate more on what is happening every 30 seconds?

Are you just getting an error at the DAQmx Read and then having to re-set up a DAQmx task?

If so what error(s) are you seeing?

If no errors, what happens?

Does this happen every time you try to read?

One thing to make sure of is that you have the latest DAQmx driver 9.2. We noticed a rare issue with static operations in some earlier versions of DAQmx with WLS devices.

Will you try updating the driver and let me know if this improves the performance of your application?

Cheers

Corby Bryan

NIC AE-Specialist

[Mikko_Tepponen]

Hi Corby,

We do have the latest driver (9.2) in use. Here's how the scenario goes.

1) WLS-9163 is set up to use the wireless WPA-PSK connection to WLAN AP using MAX

2) Device connects to AP nicely

3) After a while (random amount of time from 15 sec to 3 hours) - WLS9163 drops out of the wireless network. When this happens we are seeing errors on the WLAN AP side. Invalid EAPOL keys and so on.

4) Recovery could happen or not - in some cases the wireless connection is restored in a few minutes, sometimes the recovery needs a power off/on for recovery

We been testing this with a simple C# -application that reads the digital inputs and writes the results into a file, If timeout occurs we write NotOK line. So we are getting around 80-90% of the queries through on normal operation state (with the 30 sec interval and WLS LINK led light up on the device), but even that is tolerable. The problem is the fact that the device keeps dropping of the wireless completely (WLS LINK shuts down) and does not recover from it.

Regards,

-Mikko-