I am working on medical instrument that runs an embedded linux. The instrument currently prints to LW450 printers (discontinued) using the cups driver to print to a file and then copying the file to /dev/lp0. When I plug in the newer LW550, the OS recognizes the USB device class and creates /dev/lp0. But when I send the commands listed here under "Driver Only Package" the printer only responds to the version command .
I'm hoping someone else has encountered this and has an idea on what is going on.
I contacted Dymo and received an answer to this problem. Dymo provided a technical reference document with the latest protocol changes. The new protocol includes a lock feature where a user can "lock" the printer so that other users will know it is in use. While locked, the printer will not respond to commands other than version and status. I was unable to get the status command to work previously because the status command now includes a 3rd byte to request the lock be set or cleared.