I'm using the last example in: [https://unix.stackexchange.com/questions/219004/pipe-a-bin-file-into-xmodem-transfer?newreg=4e700c981e244fa3aa985712841c6033][1]

I keep getting wctx:file length=0 after the sz command. I'm actually opening the serial connection with minicom Minicom is botching the transfer. So, after I get to press enter to begin update in the minicom window, at which point the normal course is to go into the menu, select S for send, choose Xmodem, locate the firmware file and select it, at which point the transfer begins and fails almost immediately;

I move to a different virtual terminal window, and run sz -X -k -b -vvv - /tmp/sz_fifo > /dev/ttyUSB0 < /dev/ttyUSB0 after which I receive sz 0.12.21rc mode:1 sending s20806.lsz 0 blocks: give your Xmodem receive command now and I move into the minicom window where it still says to begin update press enter I hit enter, and get this in the sz window Xmodem sectors/kbytes sent 0/ 0kretry Timeout on sector ACK the last part repeated several times, then retry count exceeded followed by mode:0

I don't know if the fifo is empty, if I need to select Xmodem protocol in minicom, or what! I'm about to try using Windows for this job. I am far from from expert on modem protocols and fifos. Although I started somewhere around Debian Woody.