Are there any special considerations when using the 1102 to measure TCs, RTDs, and thermistors?

[Steely]

Hello,

I would like to use an 1102 to measure RTDs, TCs, and thermistors.
I know I need to excite the thermistors and RTDs with a 1581.

Will the 1102 allow a mix of differet transducers at the same time (on separate channels of course), or must I configure the whole card as if I were measuring 1 type of transducer?
Will LabView allow me to configure the module this way, or must I use a separate 1102 for the RTD/t'stors?
Will the RTD's and thermistor input signals be considered floating if the 1581 is used in the same SCXI-100x chassis as the 1102?

I am new to LabView, but am learning, and am preparing to make a purchase.

Thanks,
steely

[Marni]

Dear Steely,

You can definitely use multiple transducers on one SCXI-1102. DAQmx takes care of all of the scaling for you, you just specify the channel and transducer type. Since you are new to LabVIEW, you should consider using the DAQ Assistant. You can add all of your transducers using the same DAQ Assistant, so programming is very easy. With the DAQ Assistant you don't have to specify if the device is floating or not, it can tell based on the configuration you set. Have a great day!

Sincerely,

Marni S.

[Steely]

Dear Marni,

Thanks for the valuable info - this gives me some real lattitude. (as well as some confidence in my selection).
I do appreciate the help.

Regards,
Steely

[Logan_K]

Steely,

I would like to add one important piece of information. Marni was correct that the software will fully support different sensor types, but RTDs and Thermocouples require slightly different hardware configurations to work properly. Thermocouples require ground reference (ideally through a bias resistor), and optionally a pullup resistor for open thermocouple detection. RTDs and thermistors, on the other hand, cannot have any pullup and bias resistors because they will generate offsets in the measurements.

The SCXI-1303 terminal block is designed for thermocouples because it has pullup and bias resistor packs pre-installed - but with the appropriate modifications it can easily support both thermocouples and RTDs and Thermistors. Right out of the box, the RTDs and thermistors won't work with this terminal block, so you will need to manually remove the pullup and bias resistor packs for the channels that your RTDs and thermistors will be connected to. This is actually quite easy, and all the information you need for doing this is in the SCXI-1303 Installation Guide: http://digital.ni.com/manuals.nsf/websearch/9DA3B7D5C7F572F986256694004DEFE6

I hope this helps.
Logan

[Steely]

Logan,

<had a nice reply all set to go and then I inadvertantly wiped it out.>

I will definitely check thru my I/O when I map it out.  I really appreciate the help.  I certainly am with you on the pull-up issue - but I will need to investigate the gnd reference.  I was trying to see if there were any showstoppers out there wrt to picking out these items for my order, and all info helps.

One thing for NI - there is no shortage of documentation.

Thanks again,

Steely