How to wire VI for 2 encoders using NI9401

Question

I have the attached vi that measures period.  My understanding is that the NI 9401 can measure period for up to 4 encoders at once.  Do I need one DAQ sequence per encoder, (e.g. the attached vi should measure period for 2 encoders simultaneously)?  I want to run up to 16 encoders, so, do I need to copy/paste this code 16 times in order to collect period data for 16 encoders simultaneously?
I am using cDAQ9174 and NI 9401.  My understanding is that the 9401 can measure up to 4 encoder signals.  If I put a second NI 9401 into the cDAQ9174, can I measure 8, or does the cDAQ9174 limit the number of counters that can be accessed independently?  If I have to use two cDAQ9174's, plugged into one PC, does Labview recognize the eight slots as unique, e.g. 1-8, instead of two sets of 1-4 for the addressing of the channels? 
Any generic advice on measuring many encoders (period) simultaneously is welcome.
Thanks,
Dave
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Attachments:
counter forum feb 13 2013.vi ‏31 KB

Answer 1

-          Even if you put two NI 9401 into the cDAQ-9174, remember that the counters are in the chassis and this device just has four counters.
-          You can run counter tasks in parallel.
-          If you plug two cDAQ-9174, MAX recognizes two different devices.
Regards