irrigation_system/software/apps/slave_node/cdc-acm.overlay

&zephyr_udc0 {
	cdc_acm_uart0: cdc_acm_uart0 {
		compatible = "zephyr,cdc-acm-uart";

		modbus0 {
			compatible = "zephyr,modbus-serial";
			status = "okay";
		};
	};
};