stuart0:
Is see that the mac expects various responses after it sends query style commands like "?..". I'm just wondering what response (if any) it expects after a regular "LI=..." type command? I notice that you are still sending a Serial.println("") response in that case.If that were my project I'd start with just the basic serial comms and no laser involved. Just make sure I can correctly receive whatever the mac sends (preferably as simple char* strings) and then echo them to serial monitor. Once that works then start on the code to parse them.
BTW. I know the old laser expected 1200 baud. But now that it has gone you can probably up that to 9600 or more and make the response a bit snappier. Does the mac software allow you to set the baud rate, or is it also fixed at 1200?
The laser returns a CR LF after a successful command such as "LI=". I think the software is happy with the CR. I assume this as the the mac throws a tantrum if the correct response isnt received.
All serial comms was confirmed by my supervisor prior to hooking up the DAC. This was partially because the wall behind the laser isnt very thick.
Unfortunately the old software cannot be modified. Not can the signal path. In fact the mac doesnt even use serial - it's a parallel bus thing which is converted to serial by an intermediate (hardware) converter.