mPLS62-W: Two issues | Telit Cinterion IoT Developer Community
July 21, 2020 - 7:28am, 2541 views
we eventuelly want to connect a mPLS62-W to the internal USB of an upcoming embedded Linux product, and we are currently in the proof-of-concept phase. At the moment we have two issues with the mPLS62-W.
Issue one is that there is no stable connection with the mPLS62-W.
We are using an external "Mini PCI-E to USB Adapter" (sorry, I don't know the make or model, the quoted text is all the information given on the PCB) and two LTE atennas attached to the "Main" and "DIV ANT" connectors of the mPLS62-W.
When we noticed the first connection problems, we implemented a loop to constantly issue AT^SMONI after the initial setup.
It seems that the first six or so responses include "CONN" (but never long enough for one of the cdc_ether ports to get a link), while it's mostly "NOCONN" afterwards (as in, the longer the loop runs the more the connection ratio tends to 1%). The signal strength is always below -100, while the signal quality ranges from good to fair. An LTE smartphone at the the same location seems to work fine.
We were suspecting an issue with the USB adapter and tried to use an older embedded PC with a Mini PCIe slot that already had a modem card with a PHS8-P.
And here is the second issue, the mPLS62-W is not recognised in the Mini PCIe slot at all.
Here is the "dmesg" log with the mPLS62-W in the external adapter and the PHS8-P in the internal Mini PCIe slot to prove that it works (PHS8-P is recognised by usbserial and the option driver, while mPLS62-W works with the cdc_acm driver):
[ 6.383068] usb 1-1.2: device descriptor read/64, error -110
[ 6.581753] usb 1-1.2: New USB device found, idVendor=1e2d, idProduct=005b
[ 6.581776] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 6.581783] usb 1-1.2: Product: PLSx
[ 6.581788] usb 1-1.2: Manufacturer: Cinterion Wireless Modules
[ 6.614551] cdc_acm 1-1.2:1.0: ttyACM0: USB ACM device
[ 6.617124] cdc_acm 1-1.2:1.2: ttyACM1: USB ACM device
[ 6.619824] cdc_acm 1-1.2:1.4: ttyACM2: USB ACM device
[ 6.622430] cdc_acm 1-1.2:1.6: ttyACM3: USB ACM device
[ 6.625009] cdc_acm 1-1.2:1.8: ttyACM4: USB ACM device
[ 6.632465] cdc_ether 1-1.2:1.10 usb0: register 'cdc_ether' at usb-0000:00:1d.0-1.2, CDC Ethernet Device, fa:96:11:12:13:14
[ 6.638675] cdc_ether 1-1.2:1.12 usb1: register 'cdc_ether' at usb-0000:00:1d.0-1.2, CDC Ethernet Device, fa:96:11:12:13:16
[ 6.659578] cdc_ether 1-1.2:1.10 enp0s29u1u2i10: renamed from usb0
[ 6.665943] cdc_ether 1-1.2:1.12 enp0s29u1u2i12: renamed from usb1
[ 13.343038] usb 1-1.3: new high-speed USB device number 4 using ehci-pci
[ 13.432381] usb 1-1.3: New USB device found, idVendor=1e2d, idProduct=0053
[ 13.432391] usb 1-1.3: New USB device strings: Mfr=3, Product=2, SerialNumber=0
[ 13.432398] usb 1-1.3: Product: PH8
[ 13.432403] usb 1-1.3: Manufacturer: Cinterion
[ 13.435131] option 1-1.3:1.0: GSM modem (1-port) converter detected
[ 13.435536] usb 1-1.3: GSM modem (1-port) converter now attached to ttyUSB0
[ 13.436267] option 1-1.3:1.1: GSM modem (1-port) converter detected
[ 13.436489] usb 1-1.3: GSM modem (1-port) converter now attached to ttyUSB1
[ 13.437174] option 1-1.3:1.2: GSM modem (1-port) converter detected
[ 13.437398] usb 1-1.3: GSM modem (1-port) converter now attached to ttyUSB2
[ 13.438103] option 1-1.3:1.3: GSM modem (1-port) converter detected
[ 13.438330] usb 1-1.3: GSM modem (1-port) converter now attached to ttyUSB3
"lsusb" also shows both modems are found on the USB:
Bus 001 Device 004: ID 1e2d:0053 # PH8
Bus 001 Device 003: ID 1e2d:005b # PLSx
Bus 001 Device 002: ID 8087:07e6
Bus 001 Device 001: ID 1d6b:0002 # EHCI Host Controller
When the modem cards switch places, i.e. PHS8-P is in the external adapter while mPLS62-W is in the internal Mini PCIe slot, only the older PHS8-P is found:
[ 13.355774] usb 1-1.2: new high-speed USB device number 3 using ehci-pci
[ 13.448348] usb 1-1.2: New USB device found, idVendor=1e2d, idProduct=0053
[ 13.448358] usb 1-1.2: New USB device strings: Mfr=3, Product=2, SerialNumber=0
[ 13.448364] usb 1-1.2: Product: PH8
[ 13.448369] usb 1-1.2: Manufacturer: Cinterion
[ 13.451301] option 1-1.2:1.0: GSM modem (1-port) converter detected
[ 13.451639] usb 1-1.2: GSM modem (1-port) converter now attached to ttyUSB0
[ 13.452289] option 1-1.2:1.1: GSM modem (1-port) converter detected
[ 13.452625] usb 1-1.2: GSM modem (1-port) converter now attached to ttyUSB1
[ 13.453254] option 1-1.2:1.2: GSM modem (1-port) converter detected
[ 13.453572] usb 1-1.2: GSM modem (1-port) converter now attached to ttyUSB2
[ 13.454218] option 1-1.2:1.3: GSM modem (1-port) converter detected
[ 13.454557] usb 1-1.2: GSM modem (1-port) converter now attached to ttyUSB3
"lsusb" also shows that the mPLS62-W is not found on the USB when in the Mini PCIe slot:
Bus 001 Device 003: ID 1e2d:0053 # PH8
Bus 001 Device 002: ID 8087:07e6
Bus 001 Device 001: ID 1d6b:0002 # EHCI Host Controller
We know that they use different drivers, so there might be a different issue as well, but we would at least expect the mPLS62-W to be found by the USB core driver, when the Mini PCIe slot seems to work fine for the PHS8-P.
Thanks in advance for any hint that might solve this problem.
"CONN" is only shown in SMONI output when there is an actual data transfer ongoing. The easiest way to observe it would be during a file download or upload.
Could you write a bit more what connection problems you experienced? In your SMONI output RSRP -110 and RSRQ -12 mean that the signal quality is rather poor.
As for mPLS62-W I don't have experience with this device version but I fugured out that this card does not have the full support of PCI-Express standard. I has mPCI connector and will work in mPCI slot that hosts only USB. I think that this may be a problem while you connect to the second device.
Thanks for your reply, Bartlomiej.
Also thanks for clearing up what the CONN state actually means. In the AT command set under "Service states", only SEARCH, NOCONN, and LIMSRV are described, but not CONN, so I wasn't sure what CONN actually entails.
Interestingly enough, sometimes I do get additional CONNs after the first half-dozen, but it doesn't happen very often.
I'm somewhat new to the LTE communication, but even the colleague who did the software for the UMTS modem had no clue about the meaning of the numbers, so I had to do some research first. That's why I knew that everything below -100 dBm for RSRP is quite bad, and was looking for a different way to connect the modem card, since I suspected a problem with the USB adapter.
I started the loop again this morning to have access to fresh data. Of over 2000 SMONI replies 6 were CONN, the remaining NOCONN. RSRP ranges from -115 to -99 but seems to average at -113 at the moment.
I have a separate script running that monitors the link status of the two Ethernet devices created by the cdc_ether driver. According to that they never get a link, which also means that I should have a hard time trying to download something.
I probably should have compared the pinout of the two modem cards to make sure they communicate the same way. Thanks for the hint that the mPLS62-W will not work in a normal Mini PCIe slot.
I found a schematic for an adapter board in the mPLS62_mPLS8_mPLAS9_startup_guide_v02. Maybe we should try it with one of these?
Please also see this thread for the signal quality factors: https://iot-developer.thalesgroup.com/threads/response-atsmoni
If the signal is not as good as it should be I'd rather check the antenna and its location.
According to my HW collegue the majority of laptops and PDAs may have 2 mPCI slots - one is mPCI-Express x1 for wifi/bt and second is mPCI that hosts only usb without other lines.
As for adapter board it should be possible to order it for reference or tests.
Sorry for the delay, I wanted to wait till I get the new test equipment. I doubt that the antennas are the problem, because they are brand new were definitely ordered as LTE antennas.
I now have the offical Gemalto test board (L30960-N3202-A300), which also came with a set of antennas.
With 3V3 supplied via USB I also had a pretty bad connection (-109 RSRP; -12 RSRQ).
3V3 from an external connection was much better at first (around -95 RSRP), but strangely now it is more like -108 RSRP with -8 RSRQ. Still better than just with USB, but not exceptionally so.
Even when the RSRP was much better I still didn't get any link on the Ethernet ports that cdc_ethernet driver created. Am I missing something? Do I need to issue an additional command, once the modem is connected to the network, to get a link?
Could you please describe more exactly your setup? How it's possible that you have 3V3 on USB instead of 5V?
Maybe there is generally a problem with LTE quality in your location? Is it possible?
Regarding cdc_ethernet, you should send command 'AT^SWWAN=1,1' (assuming you have correct APN in cgdcont profile 1) to start WWAN connection.
BTW, please check this project:
It's the midlet, which implements custom AT command for checking signal level quality in the same way in any technology.
Sorry, that was a bit of a misnomer. What I meant was that I checked both options with the new test adpater: power over USB (where the test adapter generates the 3V3 from the 5V from USB) or with external 3V3.
I now have another antenne, which I can place outside the window on the windows sill. This leads to a much better singal strength and quality (RSRP -94 dBm, RSRQ -6 dB).
It still didn't work initially, but now it works suddenly.
Thanks to everyone who has helped out!
That's great it works now! Please let us know if you will have any more questions.