# Troubleshooting¶

This is a selection of typical problems. If your problem is not listed below, please check the issues for all related repositories:

## Could not connect to the myo motor: device not opened¶

There are a number of possible reasons:

### You do not have read/write access to the device /dev/ttyUSBn. Where n is a number¶

Verify this by running:

cat /dev/ttyUSBn

• If you get a ‘device not found’ you didn’t replace the right number for n in ttyUSBn
• If you do not get anything, just a clean return you have correct access rights. Press Ctrl+C and find the problem elsewhere.
• If you get a ‘permission denied’ then you have verified this problem. Add yourself to the ‘dialout’ group as described here: Allow your user to access the serial device.

### The configured serial number does not match the serial number of the USB2FlexRay adapter¶

Go and double check it by following the instructions here: Configure the myo_blink software example.

### You did not install the dependencies of flexrayusbinterface¶

Go and do it. No harm in doing it twice.: Install flexrayusbinterface

### You did not install the udev rules¶

• Check if there is a file called ‘30-ftdi.rules’ in ‘/etc/udev/rules.d/’:

ls -alh /etc/udev/rules.d
# if you don't get back anything try it with sudo:
# sudo ls -alh /etc/udev/rules.d

• The file should contain a line with something like this at the end:

/sys/bus/usb/drivers/ftdi_sio/unbind

• If it does, compare it with the file supplied by ‘flexrayusbinterface’. It is located at:

roscd flexrayusbinterface/udev

• If they match, there might be something wrong with these rules for your system. Try the option below.

### Something in the udev rules is not right¶

• Manually try to unload the ftdi_sio and usbserial kernel modules as described in the Manually unloading ftdi_sio and usbserial and try the roslaunch command again
• If that does help, use the manually loading as a workaround. Research udev files and how do unload kernel modules. If you are stuck or found a better solution, please create an issue on github at: flexrayusbinterface
• If that does not help find the problem somewhere else. Have you checked your permissions as in the first step?