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By loz@astorhouse.co.uk
#198171
Hi

I have Bluetooth enabled my old TM series Epson ESC/POS printer with the aid of a Max232 breakout board and an HC05 Bluetooth unit. My problem is that I need to be able to print from either of two sources, either the Bluetooth or a PC connected via a serial cable without having to plug/unplug continuously. I thought I could achieve this by tapping the Bluetooth output in to the ground and data lines on the serial cable cable. The Bluetooth works fine like this but the PC wont print al the time the Max232 is powered up. If the Max232 is not powered the PC will print normally. I think the problem is that the Max232 output is high even when there is no input thereby blocking the data from the PC. I have come up with 2 possible solutions.
1) Using the status pin on the HC05 to switch the power on the Max232 via a relay or transistor or Opto unit
or
2) Sending the data from the PC into the Max232 then outputting it as TTL then back into the Max232 TTL in to output as RS232 again?

Does anyone think neither or either will work?