The communications diagnostics mode is a troubleshooting tool for checking the interconnection between the printer and the host.  When "diagnostics" is selected, all data sent from the host to the printer will be printed as straight ASCII hex characters.  The printer prints all characters received including control codes, like CR (carriage return).  A sample printout is shown below.

NOTE: This label will be inverted when printed.

Communications Diagnostics Self Test Sample

To put the printer in "diagnostics" mode, press Setup/Exit once, then Next/Save until Communications is displayed on the LCD.  Press the Right or Left Black Oval key.  You may be prompted for a password.  The default password is 1234.  After entering the password into the display, press the Next/Save key, then change to the desired Communications mode, "Diagnostics" then send a single label to the printer.

NOTES on Diagnostic printouts:

For any errors, check that your communications parameters are correct.  Set the print width equal to or less than the label width used for the test.