how can 16bit DAC gear 12bit ADC

[jimmyjimmy2000]

Thank you for your previous answer. I tried to gear ADC on board yestoday, and find it bring another problem. I found my system working with terrible noise.I think it may because of the 12bit ADC on 7344.If I want to use 16bit DAC to gear 12bit ADC,I must increase the gearing ritio .I think it may increase the digital errors caused by 12bit ADC. Can you have other good way to solved this problem? How can I config in such condition.(I must use 12bit ADC to acqist -10V/10v, and 16bit DAC to output -10V/10V)
Thanks.

[algames]

What you seem to be using is Analog feedback. With this mode, you configure a servo output to use an analog +-10V signal connected to the ADC of the motion controller to be used as feedback, while the 16 bit DAC is used to generate the servo output.You should configure this under the Axis Configurationn section for the Default 7344 Settings in MAX. You can then use the Servotune panels to tune your servomotor properly to servo around the setpoint given by the ADC. This configuration works for most motion control systems out there since the PID loop runs fast enough that having a 12 bit ADC is not a problem when maintaining the setpoint. However if your system requires a lot of precision and 12 bits is not enough, you might considerupgrading to the 735x series controller
wyhich have a 16 bit calibrated DAC and ADC and will give a better response for high precision tuning.