Sorry, in the picture I’m using the air console as a convenient way to diagnose the issue I am having with the photon. I’m using the air console to communicate directly with the photon. The black RJ45 to DB9 is a pass through.
Normally, the air-console is connected to the equipment’s printer output (which works fine). I want to read the printer output with a photon instead. It’s probably a voltage mismatch issue I am having.
The photon USB is connected to my computer running a serial terminal.
@smn8600, if the airconsole is expecting an RS232 level signal then yup, your voltages are totally off. In fact, as @ScruffR pointed out, you could damage the Photon’s RX/TX pins since RS232 defines both plus and minus voltages in excess of what the Photon can handle. What you need is a MAX232 or similar TTL-to-RS232 level converter between the Photon and that DB9 connector. Something like THIS. It doen’t support hardware handshaking but will do fine for your application.
Is that the same thing as a “shifter”? is it correct to say that the photon is TTL and the air console is rs-232? I have to convert between TTL and RS232?
@smn8600, exactly. The airconsole is designed to be connected to an RS232 device directly, which the Photon is not. The device I linked to is like a level shifter for RS232 signals. You will most likely want to use the NULL modem adapter since that shifter does not support the hardware handshake lines, only RX and TX.
I’m going to mark this as solved as I agree with you now that I’m understanding this more and more. I thought RS232 was RS232. I’ll give this a try and report back. Thank you @ScruffR & @peekay123 so much for your time and patience on this you went way above and beyond!