SXCI 1600 analog output

[dmog]

Hello,

I am currently doing an experimental thesis for my Master's degree which ivolves capturing a water droplet impact on a metal surface (with one thermocouple embeded) with a high speed camera. A solenoid valve will be responsible for creating the water droplet. The main issue in this experiment is synchronizing three separate events: 

1. Opening of the solenoid valve 2. Triggering of the high-speed camera to start recording 3. Initiating thermocouple readings. These events must be initiated simultaneously.

A SXCI 1600 module (on a SXCI 1000 chasis) will caputure thermocouple readings and run it to a computer using LabVIEW. Is it possible to control the triggering of a solenoid valve using the analog outputs of the SXCI 1600 model? How would I go about wiring the solenoid to the SXCI 1600 if possible? Which output would be best suited for this? (PFI 0 or PFI 7)

The solenoid valve operates on 24V DC (1 amp) and can be wired to connect via BNC cable. I anticipate a signal conditioner would be needed to meet the power requirements of the valve. More info on the solenoid valve can be found here: http://www.shako.com.tw/products_detail.aspx?pid=404#File%20download 

Any help would be greatly appreciated. Thank you,

Dennis Moghul

McMaster University, Engineering Physics

[Kevin_F]

Hey Dennis,

You should be able to use the SCXI 1600 module to synchronize these readings.   I would recommend using PFI 0 since it is designed to be used as the AI start trigger.  The maximum voltage that it can output is 3.5V so you would need some signal conditioning between the 1600 module and your solenoid to meet both your voltage and power requirements.  I am not sure how you trigger the high speed camera but you can use the PFI 0 as the start trigger for the thermocouple readings.  Assuming you are using LabVIEW this tutorial provides a good start on synchronizing data aquisition tasks: http://zone.ni.com/devzone/cda/tut/p/id/3615.  For your case this may actually be more than you need since you are only triggering the start and not trying to keep the aquisition rate synchronized for your task.  For that application you will just need to use a Daqmx trigger on your data aquisition and hook it up to PFI 0.  Some more information on this can be found here: http://zone.ni.com/devzone/cda/tut/p/id/4329

Please post back if you have any questions. 

[dmog]

Hi Kevin,

Thank you for your response. As a clarification, the high-speed camera connects to a grabber board which then connects to the laptop using LabVIEW through a PCI connection. The camera grabber board has 2 TTL inputs and SW input, and 3 TTL outputs (+5 V) as well as the PCI connection. The acquisition of the recorded images from the camera and the thermocouple readings will have to be synchronized and can be done through the tutorials you sent me. Can the camera be triggered by the PCI connection alone? or does it require a signal to it's TTL input? Is the TTL input analog or digital? I am just trying to get an idea of what other hardware pieces are required and the capability of LabVIEW since I am not too familiar with either of these.

Further, the SCXI 1000 chassis has a thermocouple module on it (not sure which model) along with the SXCI 1600 module. I thought that the thermocouple readings were directly passed on to the SXCI 1600 from the thermocouple module then transferred to the laptop via USB. In other words, the thermocouple does not need to be connected to the PFI 0 channel. Only the solenoid valve will be connected to PFI 0. Is this correct?

Since I am only a beginner when it comes to these techniques and methods, your help is greatly appreciated. Thank you,

Dennis Moghul

[Kevin_F]

Hey Dennis,

You should be able to use the PCI connection to start the camera aquisition.  This would depend more on the camera than the PCI card.  You should be able to find information about how the camera needs to be triggered in the user manual from the manufacturer.  If you are using a different PCI card to get the camera input than the one used to connect to the SCXI module you will need a RTSI cable to connect the two cards so that they can share the same sample clock.  More information on the RTSI cable connection of the cards can be found here: http://zone.ni.com/devzone/cda/tut/p/id/5471. You are right that you should only need to connect the solenoid to PFI 0 since you should be able to share the clock signal and trigger within the SCXI chassis.  Please post back if you have any additional questions.  

[dmog]

Hello,

To clarify, the acquistion time line is as follows:

- at time = 0 seconds, the solenoid valve will be triggered to open, the thermocouple readings will begin and camera recording will start

- the valve opens only once at t = 0 seconds

- temperature readings and camera recording will both occur at 1000 Hz for a maximum of 3 seconds

After discussing some of the features of the speed camera with the manufacturer, a few changes to this setup have been realized. The camera PCI connection is not enough to trigger the camera. Instead, the PFI 0 on the DAQ will need to connect to the camera grabber board which has a dedicated BNC input for triggering camera recording. By using the camera's software to accpet external triggers and in coordination with LavView, this should allow both devices to share the same sample clock and should make the synchornization between temperature readings and camera recording fairly simple. Is this correct?

The only issue left is triggering the solenoid valve to open at t = 0. The solenoid will have to connect to the DAQ in order to minimize signal transmission delays. Is it possible to trigger the valve using PFI 7? Assuming I am using a singal amplifer to get the correct voltage for the valve.

Again, I appreciate all the help. Thanky you,

Dennis Moghul

[Dan_N]

Hi Dennis,

The PFI 7 output is the Sample Clock signal, so it outputs a pulse at the start of each analog input scan. Based on your requirement to turn on the solenoid valve only once at t=0, you cannot use PFI 7 to

trigger it, as PFI 7 effectively outputs a square wave. You can read this in the manual for the SCXI-1600, found here: http://www.ni.com/pdf/manuals/373364c.pdf. Instead, try using a BNC splitter to send the trigger from PFI 0 to both the grabber board and the solenoid. Please respond to this post if you have any more questions.

Best,

Dan Nelson

Applications Engineer

[dmog]

Hi,

How can I configure PFI 0 on a SXCI 1600 module to output an analog voltage? In using the LabVIEW block diagrams, PFI 0 is not listed in the physical channels pull down menu. How can I get LabVIEW to recognize that PFI 0 should act as an output? I've tried looking through the Instrument Explorer to configure SXCI-1600, however, I can not access its properties.

Thank you,

Dennis Moghul

[Kevin_F]

Hey Dennis,

You will not be able to output an Analog Voltage Signal with the PFI line.  You can use them as a digital pulse to use as a trigger for your devices.  For more information on exporting this signal you can check the M Series user manual which can be found here: http://www.ni.com/pdf/manuals/371022k.pdf.  Please post back if you have any additional questions.