10-25-2011 04:48 PM
Hello,
I am working with a NI 9411 module.
I am looking for a spec. for the signal wire, and the maximum length of signal wire
that is suggested between the sensor and this module.
Thanks for any help or suggestions.
10-26-2011 02:44 PM
nrel1,
Signal wiring depends on a number of factors. I would recommend starting with the Field Wiring and Noise Considerations Tutorial. Although it was written for analog signals, it contains important concepts that should be considered in any type of wiring. Cable construction is one of the most important factors to address. These construction parameters set impedance properties that will eventually attenuate and/or delay your signal (Ohm's Law).
Most communication protocols set maximum line lengths. For instance, USB 2.0 has a maximum cable length of 15ft, Cat 5 Twisted Pair has a max length of 300ft, and Fiber Optic has a max cable length of 28 miles. It all depends on your application and the conditions present.
Field Wiring and Noise Considerations
http://zone.ni.com/devzone/cda/tut/p/id/3344
Regards,
Alexander M
Applications Engineer
National Instruments
10-26-2011 02:49 PM
Thanks for the information, I will take a look at the link.
The signal I am measuring is TTL, basically a pulsed square wave, where the frequency of the pulse varies.
I did some searching and could not find a standard for the maximum cable lenght for TTL.