The RAMBo just received is exhibiting the same behavior as the RAMPs. Using the Arduino IDE on both a Raspberry Pi and PC, it won’t connect with the USB serial port at any speed. It shows garbage characters at most speeds, but at 250,000 baud, it displays “Error while setting serial port parameters: 250,000 N 8 1”. When attempting to connect, the RAMBo does blink the external LED twice, and then the on-board LED once. The same setup, same cables, will connect to an Arduino UNO. I can send it a Hello World program and have it read and write successfully at 57,600 baud.
In hoping that the RAMPs controller was not fried, or I could swap out the Arduino for a spare Mega, bought ages ago, I did not cannabalize power supply that came with the MPCNC kit. I attached the RAMBo 6 pin power connector to a Mean Well NES-350-12 12V 350 Watt Ul Switching Power Supply 110-240 Volt that I bought 1-1/2 years ago for another project. It has very good reviews. Each connector on the Mean Well was connected with 12 gauge stranded wire to the corresponding RAMBo connector. My DMM showed 12+V on each of the 3 sets of connectors. Initially, I tried to hook up the X-axis and 3 of the minimum endstops (NC). When that did not work, I removed them, leaving just the power connector and USB. It still will not connect. This is beyond frustrating. I am not sure my next debugging step should be. Is there a QA test I can run against the board? Thank you.