Hello, @sh_dhanasekaran,
Starting with the error message that you are currently receiving, there are a few more checks that we need to perform to identify the issue:
1. There are two models in the s32k3xx_simple_s32ct example. The model that is downloaded onto the hardware target is called s32k3xx_pil_target_s32ct, and the host model s32k3xx_pil_harness_s32ct that is used to connect Simulink to the hardware target using serial communication. In order to successfully communicate, the COM port must be set in both models.
2. Besides the COM port, in some cases we also need to change the Hardware UART selection. I'll quickly walk you through this process.
The MBDT for S32K3xx generates code based on RTD (Real Time Drivers) MCAL components. The configuration of the UART component used for serial communication is done using an external
configuration tool (S32 Configuration Tool integrated in our toolbox or the EBtresos tool that needs to be downloaded). We provide a default configuration (for both EBtresos and S32CT) for all the hardware parts supported in our toolbox. This default configuration includes multiple configured components and is used by the model during the build process.
For the PiL example mentioned above, you are using the internal configuration tool, S32CT, and a default configuration project for S32K344-Q257. In this pre-configured project that we are providing, the Uart component has two channels configured (UartChannel_0 and UartChannel_1). UartChannel_0 configures the LPUART6 instance on the board and UartChannel_1 corresponds to LPUART13.
LPUART6 is routed to the EVB's OpenSDA chip. The MCU's LPUART13 instance is connected to ChannelB of the USB2Serial converter on the EVB. When you connect the board to the PC via the USB2Serial port, DeviceManager will display two COM ports for both FTDI channels; typically, the higher COM port number corresponds to our LPUART13 instance (it depends on how Windows assigns COM port numbers).
In the following picture, you can see both the OpenSDA(1) and USB2Serial(2) ports on my S32K344-Q257 EVB revision:

In conclusion, if you are using the dedicated USB2Serial converter of the EVB, you should select UartChannel_1 inside both models' settings and start with the highest COM port number in the list. In order to successfully establish serial communication, you should check your schematic and make the necessary adjustments in the configuration project if your EVB has a different USB2Serial converter or a different board revision.
If you have any further questions or require assistance, please do not hesitate to contact me.
Cheers,
Victor