Simultaneous measurement

[michael081585]

I am reasonably sure that all C-series modules in a cRIO should be capable of simultaneous input/output however I would like to confirm this and there are several models that do not explicitly state this in their data sheets.  These models are the NI 9213 Thermocouple Card, NI 9402 and NI 9403 DIO cards.  I would imagine they should all allow simultaneous access on all channels but I would rather confirm this with people who have used them before I order the devices.

[Robbob · Accepted solution]

Hey Michael,

I can read your question in two different ways...

Can I do Input and Output at the same time on these modules?

The 9213 does not have output, so it is a moot point. For the 9402 and 9403, and most DIO modules, then yes, you can do output and input at the same time. you can confirm this by opening a project, adding the C Series module to a project, and going to the properties of that module. If you can configure the channels seperately, then yes. Some modules set an entire port or the entire module at once to input/output, and these would not have I and O capabilities at the same time.

Do these modules simultaneously sample?

Very few of our analog modules simultaneously sample, and they are usually referred to as Dynamic Signal Acquisition(DSA) module - 9233, 9234, 9237 are examples. They have a dedicated ADC to each channel, so we can pull a measurement from all of them at once. Most other modules, like the 9213 you mentioned, have a single ADC and a multiplexer to scan each channel one after the other, albeit very fast. So even though you can put down an FPGA node to read 8 channels at once from the module, the samples are actually slightly off phase because of the multiplexing. For digital modules, no multiplexing is required.

Message Edited by Robbob on 01-19-2010 09:46 AM