Appendix B

Troubleshooting

are various methods of achieving this reference while maintaining a high common-mode rejection ratio (CMRR). These methods are outlined in Chapter 5, Connecting AI Signals on the USB-6210/6211 Devices and Chapter 6, Connecting AI Signals on the USB-6215/6218 Devices.

AI GND is an AI common signal that routes directly to the ground connection point on the devices. You can use this signal if you need a general analog ground connection point to the device. Refer to the When to Use Differential Connections with Ground-Referenced Signal Sources section of Chapter 5, Connecting AI Signals on the USB-6210/6211 Devices, for more information.

How can I use the AI Sample Clock and AI Convert Clock signals on an M Series device to sample the AI channel(s)?

M Series devices use ai/SampleClock and ai/ConvertClock to perform interval sampling. As Figure B-1shows, ai/SampleClock controls the sample period, which is determined by the following equation:

1/sample period = sample rate

Channel 0

Channel 1

Convert Period

Sample Period

Figure B-1.ai/SampleClock and ai/ConvertClock

ai/ConvertClock controls the convert period, which is determined by the following equation:

1/convert period = convert rate

This method allows multiple channels to be sampled relatively quickly in relationship to the overall sample rate, providing a nearly simultaneous effect with a fixed delay between channels.