Serial communication hang

dwm1001
serial
pans
#1

Hi,
we have a problem with listener DWM1001.
When the listener do a resync task the serial port (usb) stops receiving commands.
You can reproduce a resync task manually through android app for example by enabling or disabling the LED of “the initiator” unit.
When resync task occurs often serial communication hang also the output of the lep command hang too then the serial is unresponsive, the only way to resume operation is to turn off the power for a few seconds to the listener unit.
We have tried with firmware version R1 and R2 the problem is the same.
Is it a known problem? There is a solution?
Thank
Regards.

0 Likes

#2

The Module software may be going back to Generic mode.
Have you tried hitting ‘enter’ twice on the keyboard?

0 Likes

#3

Hello massimo,

To enter serial mode you need to press two enters then only you can fire lep command.

The issue of serial port being non responsive might have something to do with the USB serial library that you might have used. Yes serial port stops sending value when the tag looses line of sight and continues once its back in line of sight. Accurate value of x,y and z might also sometimes stop the tag location update.

Hope this helped.

0 Likes

#4

I tried, the serial does not accept any input command after the the resync task even the enter command “@”.
I tried on about ten DWM1001, the problem is the same.

0 Likes

#5

Hi Massimo,

does it mean the module some hangs and sometime not?
If it hangs, does it reset automatically after 10+ seconds?
Can you observe some strange blinking of the LEDs when it happens?

Cheers,
TDK

0 Likes

#6

Hi,
yes, the listener performs a resync operation realigning itself correctly, after this task serial communication problems are encountered, the input mode of serial hang every times, sometimes hang the output mode too.

0 Likes

#7

Hi Massimo,

that’s strange. How the module is powered? To which device is the module attached to in order to get the serial communication?

Cheers,
TDK

0 Likes

#8

The initiator and all anchors are powered with power supply, the listener is connected to a USB port PC with Windows 10 OS.
For now I’m solving through this workaround: in order to guarantee the continuity of the service, I have installed 2 listeners for each zone and every 30 minutes I restart the initiators using J-Link Commander, I discovered that the communication channel used by J-Link is working, this allows me to reboot teh DMW even when the channel is blocked via serial port (putty).
Restarting the PC does not remove the voltage from the DWM1001 (usb port) the usb voltage is not interrupted during the restart then after rebooting DWM is still in hang state. The only way I have found for now is through JLINK.
Greetings, Massimo.

0 Likes

#9

Hi Massimo,

thanks for sharing the work-around. I don’t know why that happens in your system.
We have not experienced a such issue. Please keep us posted if you found out the reason.

Thanks,
TDK

0 Likes

#10

I think the problem is related to the application firmware layer because the serial port still communicates towards the lowest level application layer even when the application firmware does not accept and does not send communications, instead the communication with the lower layer is always stable and responsive . I tried with 2 sets of DWM1001 (24 anchors), these as listener and as initiator, the problem does not change. I assume that I am working with some buggy DWM sets.

0 Likes