Legal Removal Request

Post: I am having difficulties getting the Serial Pi Plus working, allthough using the given instructions. I have the Raspberry Pi 3 B+. Serial Pi Plus is the only connected hardware. I am running Rasbian with latest Updates and Upgrades. Below is my setup. /boot/cmdline.txt: dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p7 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait splash plymouth.ignore-serial-consoles quiet End of /boot/config.txt: enable_uart=1 dtoverlay=pi3-miniuart-bt In Raspberry configuration I have enabled the following interfaces: SSH Serial Port Remote GPIO The Serial Console is disabled When doing the loopback test, connecting pins 2 & 3 in the DB9 and using either Putty or minicom with baud rate 9600 thru /dev/ttyS0, keystrokes are not echoed, nothing appears. I am doing this under sudo, so permissions shouldn’t be an issue. When connected to external device thru rs232 I can receive data but not able to send anything. Are my settings correct? Is there a way to debug the hardware to detect possible malfunction of the Serial Pi Plus? Any advice on how to make the setup working?