The "~JA" command, as stated in ZPL Programming Guide vol.2, cancels all commands in the buffer.
We were using the ~JA at the start of every PRN file and it worked as intended on ZM400 and ZE500 models. The goal is to have only one printout in case multiple prints are triggered. So if I press "Print" 3 times, only the third label prints out.
I have tried:
- introducing the ~JA command through Zebra Designer interface
- introducing the ~JA manually in the PRN at the start of the PRN file as ~JA~; ~~JA~; ~JA
No luck. On the ZT410 nothing prints out, the printer just hangs there with the data led blinking.
Any ideas?
This is the kind of question that wants a higher level control at a lower level. If you only want 1 label to be printed after a button or print dialog is initiated, it needs to be done at a higher level than ZPL II. Sending a ~JA command typically just flushes the command buffer on a printer less than it does eliminate the ZPL that is being sent before it. In your case, you should eliminate the user's ability to hit the print button 3 times. Effectively adding a de bounce function to your higher level program. It is good however to send a flush command before sending the ZPL you want to print, in case a cached command for a label is stuck in the buffer for the printer. There have been instances where an old label will print out because I have neglected to send this command at the header of my ZPL generator.