Dear Sir,
Thanks for using the Developer Exchange.
The NI-2501 can only handle signals in the +-10V Range and the NI-2503 signals in the 60 VDC and 30 VAC(RMS).
To use the NI-4060 card with a multiplexer the best option you have is the SCXI-1127 or the SCXI-1128 module. The SCXI-1127/1128 can assume multiple configurations:
2 Wire Mode - 32X1 Multiplexer
4 Wire Mode - 16X1 Multiplexer
1 Wire Mode - 62X1 Multiplexer
Also you can use the module in Matrix configuration (32X1, 8X4)
The SCXI-1127/1128 can also handle signal up to 300 VDC or Rms.
Best Regards,
Omar De Andrade
Applications Engineer - Computer Based Instruments
http://www.ni.com/support/