I see spikes at the U2351A/U2353A's Analogue Output when Analogue Input is turned on and its frequency changes according to the AI sampling.

There is a spike on the U2351A/U2353A's Analogue Output when Analogue Input is turned on because the unused reserved AD trigger out signal from the FPGA IO function (internal FPGA) has been enabled. When AI is triggered, the AD trigger out signal that becomes enabled causes a cross talk spike at the AO channel.

Please download the hardware driver ver 1.04 or above to resolve this issue. Download the driver from the product's webpage on this website or follow this link directly: Keysight USB Modular Products Hardware Driver and IVI COM Driver