Connecting SCXI Chassis to PXI Chassis or PC

Updated Oct 30, 2018

Reported In

Hardware

  • SCXI-1349
  • Chassis for SCXI
  • Voltage Input Module for SCXI
  • Analog Output Module for SCXI

Software

  • Measurement & Automation Explorer (MAX)

Driver

  • NI-DAQmx

Issue Details

My SCXI chassis has analog input modules in it. I want to connect my SCXI chassis to my PXI/PXIe chassis or my computer/PC so that I can acquire data from the SCXI chassis.

Solution

SCXI chassis can be connected to either PXI chassis or PC. Below contains the required hardware and setup guide:


Hardware

  1. SCXI-1349 Shielded Cable Adapter

    • This adapter goes on the back of an SCXI module. Determine the specific SCXI module that should be chosen for this by reading the SCXI Quick Start Guide.
  2. 62xx or 63xx DAQ card (68-pin with analog input channels) for computer or PXI/e chassis
  3. 68-pin cable to connect the SCXI-1349 to the DAQ card

The cable will be dictated by the DAQ card chosen. See the accessories from the product page to determine the cable type that will be used with your card. For example, it can be seen from the product page for the PCIe-6351 that the SHC68-68-EPM cable would be purchased.
 

Setup in NI-MAX

Open NI-MAX and ensure you can see the DAQ card you have connected to the computer. Self-test to ensure functionality. Then, follow the steps below:

1. Right click on Devices and Interfaces and click Create New 
2. Expand the NI-DAQmx SCXI Chassis section and choose your chassis model and click Finish
3. Ensure the modules are setup properly in the Modules tab to match the physical configuration of the chassis 
4. Click the Chassis tab 
5. Ensure you have the Chassis Communicator set to your DAQ device
6. Ensure the Communicating SCXI Module Slot is set to the slot the SCXI-1349 adapter is connected to

After this, your DAQ card should be configured under devices and interfaces with the hierarchy of your chassis and the modules inside it. 

Additional Information

The DAQ card used can also be any 68-pin E Series DAQ device, excluding 61XXE devices. For example, 60xxE series could also work in the setup. However, these devices are older and not recommended for new purchase.
 

Sampling Rate Limitations

The DAQ card chosen can limit the maximum sampling rate achievable from the SCXI channels. Maximum sampling rate will be 333 kS/s or the limit of the DAQ card, whichever is slower. The sampling rate from the SCXI channels will be further limited due to multiplexing.

Due to multiplexing, the sampling rate per channel in the SCXI chassis will be further limited. This can be calculated by dividing the sampling rate by the number of channels.

For example, when using PCIe-6343, the maximum sampling rate is 500 kS/s. With this setup, maximum rate will be 333 kS/s or maximum sampling rate of the DAQ card. In this case, the DAQ card is faster, so the maximum sampling rate for the SCXI chassis will be 333 kS/s. This is then divided by the total number of channels. Using 3 modules, each with 32 input channels, that would yield 96 channels total. 333,000/96 = 3470 S/s = 3470 Hz is the maximum achievable sampling rate for any individual channel in the SCXI chassis, given this setup.
 

Daisychaining SCXI Chassis

With the hardware setup described in this article, it is possible to connect multiple SCXI chassis, sometimes also called daisychaining. Additional hardware will be required to daisychain, read more at Configuring a Multichassis SCXI System.
 

Alternative for SCXI Chassis to PC

An alternative exists for connection to a PC from an SCXI chassis. The SCXI-1600 is a module that allows USB connection to a PC. This method does not support daisychaining.

The SCXI-1600 is not supported in Windows 64-bit. For USB support of SCXI on a Windows 64-bit operating system, use a USB mass termination DAQ device with 3 ports of DIO.  Potential devices include the USB-6259 Mass Term, USB-6251 Mass Term, USB-6361 Mass Term and USB-6363 Mass Term.

Read more at Frequently Asked Questions for the NI SCXI-1600 USB Data Acquisition and Control Module.

 

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