LPC11C24 MCU to control DAC8718
Since it looks like you want to do a Read back write operation, try this:

#include "mbed.h"

CAN can(NC, NC);
DigitalOut chipsel(P2_0);


int main() {
// Init CAN
can.frequency(125000);
// Main loop
SPI device(P2_3, P2_2, P2_1);
device.frequency(1000000);
device.format(8,3); // 16 bits
chipsel = 0;
chipsel = 1; - remove this
float response;

while(1) {
    chipsel = 0;
    device.write(0x88FFFF); // dont need to care about response, writes max voltage to DAC0, look on page 47 and 48 of TI docs
    chipsel = 1;
    // wait some time here, not sure about wait timing here
    chipsel = 0;
    response = device.write (0xFFFFFF); // write NOP command and read data returned
    chipsel = 1;
    // do whatever with response
}

}