Next question. Anyone know about this?

I'm rolling my own serial interface now, using a MAX232 and some capacitors, instead of using a third party shield. I have this working so far. It works at 115200 even with only the TX, RX, and GND pins connected to the serial port.

Most of the schematics I see indicate that I must also loopback some of the pins on the RS-232 serial plug back to other pins on the same plug.

Some say I should loopback connect pin 7 to pin 8, and also loopback connect pin 6 to pin 4. Example: https://www.avrprogrammers.com/articles/max232-arduino

Others say I should do the same as the above but also loopback connect pin 1 to pins 6 and 4. Example: http://justanotherlanguage.org/content/building-max232-circuit-serial-port-communication

What is the purpose of these connections on the RS-232 plug? And are they required for the Empeg? I'm not even sure those pins are hooked up at all on the Empeg side of things. I don't think there's enough wires on the empeg serial connector for those.