Hi Delong,
What Andrew meant by the AI being fried, is that if the voltage in AI exceeds the spec of the card such that it is too far from ground, then the AI may be damaged. The best configuration is to have the chassis tied to earth ground and any exrternal circuitry also tied to earth ground. There is no need to connect the ground of the chassis to the COM of the 9264.
Regards,
Margaret Barrett
National Instruments
Applications Engineer
Digital Multimeters and LCR Meters
