I have two RCM6760 boards and noticed they act differently with the same program, specifically when it comes to the serial interface. 20-101-1321 h is able to establish serial communications on it’s 30010422-03 REV B PCB, whereas 20-101-1321 k fails to establish serial communications on it’s 30010422-04 REV A PCB. I’m hoping you could supply me with the PCB schematics because I can visually see the slight differences on the hardware. I’m hoping with the proper documentation/schematics, or advice, I can understand what needs to be done to translate my program over to the newer board.
The RCM6700 schematic is available on the Digi website.
The only physical changes between those two revisions was to the 32kHz clock and the voltage regulator at U3 (source of 1.2V). The original PCB supported two clock options (rev K on Y2 instead of rev H’s Y3), but was redesigned for the new regulator.
Which serial port are you using? Does the problem affect all serial ports on that board? If it’s all serial ports, it could be an issue with the baud rate calculations. If it’s just one port, there could be a physical defect on that single board – do you have another revision K board to test with? Do you have a logic probe to check the Tx/Rx signals on those pins?
You can open a support case with Digi regarding this issue, and provide a standalone test program that demonstrates the failure. They’ll assign that issue to me, and I have revision K hardware that I can test with.