@fossette Very well written!

I have a serious serial I/O problem that has me baffled. I just picked up on a tidbit in your final paragraph. In reference to the first Omega serial port it is at a 3.3V level. That is no surprise as the device runs at 3.3V. However, this may be at the core of my problem.

I'm getting garbage from the device over the serial port. In the first case I used a breadboard expansion to a serial-to-USB converter. I highly suspect the Omega could not drive the converter adequately as the breadboard signals are true device signals, and the converter was overdriving the Omega serial receiver. On the Omega I connected to both serial ports with the same effect, to no surprise.

In the second example, garbage abounds as well. However an expansion dock is in use and is powered up by 5V only being connected to Tx1 and Rx1. Bi-directional garbage. Is this interface also at 3.3V?

I'd appreciate a reply. FYI, here are my next steps. Somewhere, somewhere, somewhere in the docs find what these interfaces are spec'd at. Put a scope on the Tx1 port to check signal level and quality.

Here's another data point which points to a drive level issue. In one test config I have a sensor device driving the Omega Rx1 twice a second with perhaps 60 characters each message. Only a small percentage of the characters get through at random times, and are unrecognizable.