Please send scope shots of your gathered signal. Was the offset showing when shorting the inputs to ground? You can also check the ground connection of the source to the AD7609 eval board and make sure that it connected with a short wire and the same length for V+ and V- as possible.
Thanks for your reply.
I tested AD7609 eval board too.
I attached the file( signal waveform and test environment).
In the waveforms, the first is for channels 1 and 3, the input for 1.0V, and the channel 2 is open. This will swing +40 ~ 50mV of channel 3 voltage.However, if you input 1.0V for all channels 1, 2, and 3, the voltage is read very steadily.The cause is unknown.The equipment I develop must use the channels randomly, so I need to read the data reliably even without interim use.Please help me.
AD7609 allows simultaneous sampling of all analog input channels.All channels are always converted The results for any unused channels are still included in the data read. It's recommended to connect all unused analog input to AGND.
I have tried various tests on the AD7609.