Issues with SPI readWrite using Simulink Arduino Support Package

I'm using the Simulink Arduino Support Package to interface between an Arduino Due and a TI DAC714 using SPI protocol.

Configuration parameters used:

The SPI clock is set to 4000 kHz.

Slave Select Pin = 10;

The DAC714 takes in 16-bit data in binary two’s complement.

So to test out the SPI, I am sending a constant 6 in uint16 into the SPI readWrite Block Function to test the SPI connection.

The issues I am coming across is that I'm not seeing any changes in my pins:

1) I'm not seeing a serial clock signal when checking between the SPI CLK pin and GND in an oscillascope.

2) I'm also not seeing a data bit code between SPI MOSI pin and GND in the scope.

3) I'm seeing non-uniform switching (~10 us) in my SS pin 10 and GND in the scope.

I'm not sure what the SPI readWrite function is doing in Simulink and I tried to follow the Simulink IO video from Mathworks Youtube on how to program SPI with an EEPROM. I'm assuming that the function automatically converts the uint16 input into binary.