#include <SPI.h>


const int ltcs = 3; //active low ADC enable

float ch0=0.0;
float ch1=0.0;
byte b0; 

void setup() {
SPI.begin();
SPI.beginTransaction(SPISettings(200000, MSBFIRST, SPI_MODE0));

Serial.begin(9600); // set the baud rate

pinMode(ltcs, OUTPUT);
digitalWrite(ltcs, LOW);
}

void loop() {
if(Serial.available()){

   int data = Serial.read() - '0';
   if(data>0){

   getdata2(ch0,ch1);
    //getdata2(ch0,ch1); //run multiple getdata2 to test multiple conversions
   //getdata2(ch0,ch1);
    //getdata2(ch0,ch1);
   //getdata2(ch0,ch1);

    Serial.println(0.2);
    Serial.println(0.4);


  }
  }
  }

 void getdata2(float &ch0, float &ch1) {
   ch0 = 0.0;
   ch1 = 0.0;

   for (int i = 0; i < 2; i++) {
      delayMicroseconds(1);
     while (digitalRead(MISO) == HIGH) {
     }
     if (digitalRead(MISO) == LOW) {
       b0 = SPI.transfer(0x00);
       b0 = SPI.transfer(0x00);
       b0 = SPI.transfer(0x00);
       b0 = SPI.transfer(0x00);
   }
   }
   }

#include <SPI.h>


const int ltcs = 3; //active low ADC enable

float ch0=0.0;
float ch1=0.0;
byte b0; 

void setup() {
SPI.begin();
SPI.beginTransaction(SPISettings(200000, MSBFIRST, SPI_MODE0));

Serial.begin(9600); // set the baud rate

pinMode(ltcs, OUTPUT);
digitalWrite(ltcs, LOW);
}

void loop() {
if(Serial.available()){

   int data = Serial.read() - '0';
   if(data>0){

   getdata2(ch0,ch1);
    //getdata2(ch0,ch1); //run multiple getdata2 to test multiple conversions
   //getdata2(ch0,ch1);
    //getdata2(ch0,ch1);
   //getdata2(ch0,ch1);

    Serial.println(0.2);
    Serial.println(0.4);


  }
  }
  }

 void getdata2(float &ch0, float &ch1) {
   ch0 = 0.0;
   ch1 = 0.0;

   for (int i = 0; i < 2; i++) { //Do twice to retrieve both Channels   
     while (digitalRead(MISO) == HIGH) {
     }
    
       b0 = SPI.transfer(0x00);
       b0 = SPI.transfer(0x00);
       b0 = SPI.transfer(0x00);
       b0 = SPI.transfer(0x00);
   }
   }
   

The arduino code is as follows(although simplified)

The arduino code is as follows. The code has been simplified to just the necessary byte reads from the ADC, all other code has been removed to ensure the delays are coming from the SPI.transfer(0x00). The full code retrieves 4 bytes per channel and converts this to voltage and returns these values.