multiple scxi 1127 switches scanning, dmm 4070

[alex b.]

Hi,

I am using 2 switches SCXI-1127 in a PXI/SCXI combination chassis. The readings are done through a dmm 4070.

I need to scan 60 thermocouple channels, i.e. 32 on the first one and 28 on the second switch. Now, I found http://zone.ni.com/devzone/cda/tut/p/id/3658 stating that a scanning multiple SCXI switches is using legacy DAQ functions in niSwitch for these specific siwtch cards (1127).

What version of niSwitch was it? Is it still true now? Why is that? Or should I use the new way using DAQmx?

thank you

alex 

[chericks1]

Hi Alex,

This is still the case with NI-Switch 3.3.1.  Due to hardware limitations, scanning multiple SCXI-1127 modules is not a simple task with the NI-Switch driver.  I would recommend using the DAQmx example "DAQmx Multi Switch Synch.vi" if you are performing synchronous scanning.  I have taken a screen shot of the front panel of a working VI to help get you started.

In general, it is more efficient to use DAQmx when scanning multiple switches.  When using NI-Switch to scan multiple switches, it is necessary to maintain a session for each switch module.  When using DAQmx Switch, you need only open one task.  Using DAQmx Switch increases programming efficiency, keeping your code neat and maintainable.

If you need further explanation or if you have further questions, please let me know!

Chad Erickson
Switch Product Support Engineer
NI - USA