How do I syncronize and implement MANY DAQ cards?

Question

I need to acquire 30 channels of analog data at 400 kHz scan rate (all 30 channels is one scan. It would be preferable to convert all 30 cahannels simultaneously and stream data to disk for long data collection times. Signal conditioning such as integrators/sample and hold is an option to reduce the simultaneous sampling requirements.

Answer 1

Do you already have DAQ boards or are you looking to purchase? If you already have the DAQ boards, you can synchronize them together by sharing the clock source between them. This can either be done externally or internally with a RTSI cable.
If you are wondering what DAQ boards to use, there are several options.
If you can drop your scan rate all the way down to 40 kHz, you can use one NI 6071 device to scan in all 30 channels. If you must sample every channel at at 400 kHz, you will need to use multiple DAQ boards, and possible multiple systems. With the 6070E board, you can sample 3 channels at 400 kHz, though you would need ten of these boards. Another option would be to go with a simultanious sampling boards. The NI 6110 has four analog inputs with a 5
M/samples per channel rate. You would need several of these as well.
Once you have the DAQ boards, you can synchonize them by having them all use the same scan clock. If the boards are in the same system. You can internally connect them using a RTSI cable. (up to five devices.) This way, you do not have to externally wire the clock. Since you will probably have to use multiple systems, you will need to use external wiring to connect the clock source to the multiple systems.
Let me know if you have any questions about this.
Brian