DC2873A-B (LTC2688) + DC2026C (Linduino) no communication

Hello there,

I have a DC2873A-B board (with the LTC2688 IC) connected to the Linduino board (DC2026C), which is connected to the host PC. The linduino is loaded with the DC5908 sketch via Arduino software. 

The V1+/V2+ are tied to VCC (5 V) and the V- is tied to GND.

I open the ACE software.

The boards are discovered. I can click to toggle LED and see the TX/ RX leds blink on the Linduino:

I go to the found device by double click and immediately see an error in the bottom:

The same error is in the screenshots from the DC2873A-B user guide, so I ignore it. 

I go to the device view and enter new DAC value for channel 0, Register A. Press Apply changes. Looking at the scope with a probe attached to the SCK pad, there is no communication.

TX/RX LEDs on the Linduino also do not blink. There is no DAC output updated (VOUT0). Read all also yields no communication as well. The registers are updated however in the GUI it seems:

(But still no VOUT0 output change)

I have no idea what I am missing. I would appreciate all help.

EDIT: I have checked what happens on the SPI lines when the devices are powered on and the ACE software is turned on for the first time. I could then observe some communication on the SCK and SDI lines, but not SDO and #CS/LD- it seems that the LTC2688 is not responding, maybe due to the #CS line being in high state all the time?



Added more scope info.
[edited by: lprzenioslo at 9:22 PM (GMT -4) on 6 Oct 2021]

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