Five SUSETMX ESD channels are connected to the new 28 bit DAC and looped back into ADC4 on PEMEX.

The connections are made using a mux matrix named DAC_MTRX in the ETMX model.

L3_ESD_DC -> ADC channel 0

L3_ESD_UR -> ADC channel 1

L3_ESD_LR -> ADC channel 2

L3_ESD_UL -> ADC channel 3

L3_ESD_LL -> ADC channel 5

The 20-bit digital DAC output going to the ESD is sent through the mux matrix and then scaled with a gain of 51.  This gain takes into account the 8 extra bits on the 28 bit DAC, the 10x gain in the AA chassis, and the 2x voltage range of the A2D compared to the DAC. 

The gain results in close to max A2D range for a railed 20-bit DAC.