Orin Nano Jetpack 6.0 UART1 issue

Robotics & Edge Computing Jetson Systems Jetson Orin NX
5

Do you mean the following one?

UART0 => UART2(PX04, PX05, PX06, PX07): uartb@3110000 (NA) - Unused => To M.2 Key E

If so, please enable the node serial@3110000 in device tree.
Please also note that /dev/ttyTHS0 is not enabled by default.
You also have to modify the following line in device tree.

        aliases {
                ..
                rtc1 = "/bus@0/rtc@c2a0000";
                nvdla0 = "/bus@0/host1x@13e00000/nvdla0@15880000";
                nvdla1 = "/bus@0/host1x@13e00000/nvdla1@158c0000";
                tegra-camera-rtcpu = "/rtcpu@bc00000";
                serial1 = "/bus@0/serial@3100000";
                serial2 = "/bus@0/serial@3140000";
+               serial3 = "/bus@0/serial@3110000";
        };

and the /dev/ttyTHS3 should be available for UART0 (0x3110000)