Major code differences PXI vs. SCXI

[LV_Addict]

How similar is the code written for a SCXI and PXI target? Is it reasonable to say that if you're comfortable targetting PXI devices, that the knowledge is transferable to SCXI. We are thinking of moving to that platform and I was wondering what the inpact might be on my code.

Secondly, is PXI newer than SCXI? It seems to me that you can do most of the SCXI stuff on a PXI. I must be wrong about this, else why would there be combination chassis?

much thanks in advance

[Ben · Accepted solution]

The big difference is the channel naming conventions are different since SCXI adds another level of multiplexing for your I/O devices.

Yes PXI is newer than SCXI.

PXI is a ruggedized verson of PCI which the standard bus you find in PC towers. With the right interface you can do DMA and anything else supported by the PCI bus.

SCXI is a bus structure that allows the addressing of i/o points and routing them to an A/D converter. For ages this A/D converter was on a PCI or PXI devices (that also contrlled the SCXI selection logic) but recently the A/D converter and control logic have been placed a USB device so PCI or PXI are not required in all SCXI cases any longer.

Just trying to help,

Ben

[LV_Addict]

Perfect, thanks Ben,

I'll need to read up more on SCXI. It sounds like if you're just doing simple digital I/O or analog I/O, you are not getting the  full advantage of SCXI. However (and correct me if I'm wrong) the SCXI system may be more apt to directly connecting strain gauges or other types of analog signals. Maybe one less "buffer board", or one less signal conditioning board is required with the SCXI.

[Ben]

That's how I understand it.

SCXI was designed for high channel counts. I believe the cost per I/O point is lower since only one A/D converter is required.

Ben

[LV_Addict]

Yep, it looks like you can get an analog input system going very quicky. The only thing that's a bit confusing to me is the controller. Other than the new USB controller you mentioned, the other controllers listed in the SCXI configuration tool are DAQ devices, for example, a PCI DAQ or a PXI DAQ (many of which I've used) is also a "Controller" to control your SCXI devices. (?) 

It also looks like you can't go 100% SCXI (chassis and all) and have a controller in the chassis that is also your computer for the entitre system. Looks like a PXI/SCXI combo chassis is the way to go if that's the requirement.