Using Mikron m770s IR sensor with labview

[PollardVT]

I am using a Mikron m770s IR spot sensor with a PXI chassis and LabVIEW. The equipment I have is the m770s (4-20ma output), an SCC-C120 current input module, SCC-68 I/O connector, NI-PXI-6221 M Series DAQ with DAQmx, and a NI-PXI-1033 chassis.

I tried setting this up in MAX, and it seemed to work, but when I tried to pull actual data from the sensor in LabVIEW, I received nothing. 

I hope someone can point me in the right direction. 

Thanks!

[Chris_D]

Hey PollardVT,

Let us first isolate whether the issue is with the DAQ device, signal conditioning module, or with your sensor.

It sounds like you have already successfully added your device into the Measurement & Automation Explorer (MAX). You can test the functionality of your DAQ device using the Test Panels in MAX. Here is a quick tutorial on the test panels.

Using Test Panels in Measurement and Automation Explorer for Devices Supported by NI-DAQmx
http://zone.ni.com/devzone/cda/tut/p/id/4638

Also, have you added your SCC-68 and SCC-C120 into MAX? This must be done first before you can properly make current measurements with your device. Details on doing this are in the SCC-68 User Guide under the Taking Measurements with NI-DAQmx section.

SCC-68 User Guide and Specifications
http://digital.ni.com/manuals.nsf/websearch/6ECC13E530315D21862571C3004FF365

What does your LabVIEW program look like? Are you reading the correct channel?

Regards,

[PollardVT]

Chris -

Thanks for the quick reply. I will try your suggestions at my next opportunity, and I will let you know how it goes. 

PollardVT

[PollardVT]

Chris -

I have followed the step you provided regarding the configuration of the SCC-CI20 module, and the SCC-CI20 appears under the SCC-68 which appears under the NI-PXI 6221 which is under the NI-DAQmx Devices in the configuration tree in MAX.

My device (the IR sensor) is connected to Mod1/ai0 (terminals 1&2 on the SCC-CI20), and when I run the test panel, it tells me that it is getting a constant signal of 0.0213mA. As best I can tell I am reading the correct channel. I also checked Mod1/ai1 to which nothing is connected, and I was shown the same signal. I tried this again with all Mods and channels, and I got the same continuous signal for each even though there are no Mods in those connector blocks.

The LabVIEW program I created is very basic. It has a waveform graph which receives its signal from the DAQ Assistant under the "Express" section. I configured the DAQ Assistant to acquire an analog current signal from SCC1-Mod1(SCC-CI20)/ai0 with an internal shunt resistor. I set the timeout to -1 so that the DAQ doesn't timeout. I did not change any other options. I also have the output from the DAQ Assistant going to a Write Measurement File.

Does it sound like I have set up everything properly?

Thanks,

PollardVT

[PollardVT]

Chris -

In my last msg I wrote that "My device (the IR sensor) is connected to Mod1/ai0 (terminals 1&2 on the SCC-CI20)." I do not have it connected to terminals 1&2. It is connected to terminals 3&4 which are also labeled as ACH(X). I just wanted to correct myself. Sorry for any confusion.

PollardVT

[Paul_C.]

Hi PollardVT,

 It looks like you have things setup on our side correctly.  Are you able to verify the output of the sensor with a DMM?  Are you seeing the signal you expect in either test panels or the DAQ Assistant?  I'd like to confirm that the sensor is working and outputting properly before we try and diagnose if there is something wrong with the setup.

Regards,

Paul C. 

Message Edited by Paul C. on 11-03-2008 11:44 AM

[PollardVT]

Sorry for the delayed response, but my IR sensor had a firmware malfunction and had to be returned for repairs. I have finally received it back. 

The IR sensor is putting out a 4-20mA signal. This was verified with a DMM. The signal also behaves as expected when focused on a target. But still when I connect the IR sensor to the SCC-CI20 module, I get no signal.

The test panels in MAX show a very slowly but continuously increasing current signal. The same signal is shown when I look at other channels that have no inputs. 

Thanks,

PollardVT

[John_P1 · Accepted solution]

Hi PollardVT,

A slowly, continuously increasing signal would be expected behavior for an unconnected terminal on a DAQ device (more information in this KnowledgeBase).  I would first double-check that everything is wired up correctly and there are no bent pins or loose connections.

You might want to try replacing the input resistors on your SCC-CI20.  Information on how to do this can be found on page 4 of the SCC-CI20 manual.

If this does not help, I would check to make sure that the DAQ 6221 / SCC-68 combo is functioning properly.  The SCC-68 manual describes how to set up the SCC-68 as a screw terminal (on the bottom of page 28).  Selecting to use the SCC-68 as your terminal block will give you access to all of the inputs on the DAQ device.  I would try to connect a known voltage source (pins 8 and 14 are +5 Volts) to one of the analog input terminals to see if you can measure a voltage signal.  This will verify if your 6221 and your SCC-68 are properly connected.

Let me know how these suggestions work out.  If you are still having problems, could you send a screenshot of your hardware configuration in MAX?

-John 

[PollardVT]

John -

I have fixed the issue. I did not read the part about the connection from AI SENSE to AI GND (terminals 62&67) on the SCC-68 that must be used when analog input SCC modules are installed. I am now getting the expected response. Thanks for your suggestions. 

PollardVT

[SFAROKHI]

Dear PollardVT

I have the same problem as you.

I have the same signal on all the channels.

Could you mind please let me know what is the solution ? ( I mean  AI SENSE to AI GND!!!!!_

Thanks

Shahab