PCI 6120 & BNC 2110

[ccurtis]

I downloaded this example: http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=DC9C549F7FDC1973E034080020E74861&p_node=DZ52000_US&p_source=External from this web site. I am using a BNC-2110 and have connected two sensors to it. I modified the code to show both inputs. However, I am having difficulty in figuring out how I can show both traces on the same graph, but show them as separate traces. Can anyone point me in the right direction? Is this possible or do I have to use a separate graph for each input from the BNC-2110? Any help would be appreciated!
Many thanks in advance for any assistance.
Charlie

[Dennis_Knutson]

If you have specified multiple channels, the graph will automatically display them. What do you have as input in the Physical Channel control? It should be something like Dev1/ai0:ai1.

[ccurtis]

Hey Dennis,

Thanks for the quit response! In the Physical Channels Control I have Browse and then four channels. I renamed my device PCI6120 form the default Dev1 so I have PCI6120/ai0 thru ai3. When you say if I have specified multiple channels I am not sure I follow? The downloaded sample shows all four physical channels in the control, but only graphs the channel showing in the control. I.E. If I select PCI6120/ai1 then I can run the vi and when it completes the run it will graph that channel only. Is there a way to have it do as you say and show all traces for all channels in the physical channels control?

Thanks,
Charlie

[Dennis_Knutson]

The downloaded example only shows Dev1/ai0 - at least on my pc without a DAQ board. When you click the physical channel arrow, you are selecing just 1 of the 4 that you've got configured. Enter on the same line in the physical channel control, multiple channels like I said and you will acquire as many as you specify instead of just ai0, ai1, ai2.

[ccurtis]

Ok got that Thanks! Now is there a way to separate the two traces? Have one of the traces physically separated from the other in the same graph? I appreciate your help!
Thanks,
Charlie

[Dennis_Knutson]

It's not quite so easy as a chart where you can stack them in different windows. One way is to create a duplicate scale. this is done by clicking on the amplitude axis and selecting Duplicate Scale. If you want, you can click on either one of the axes and select swap sides. Then you have to assign each plot to the scale. In the plot legend, click on the plot name and select Y Scale. You will see listed the two different Y axes. Assign one plot to one axis and the other plot to the other axis. For both Y axes, it will help if you turn off Y scale autoscaling. Then you can change the formatting of both Y scales. When the property window opens for a specific scale, go to the scales tab. There is an entry ther for offset. You might have an offset of 1 for one plot and an offset of -1 for the other. Note that when you do this, the axis values won't match the actual values of your acquisition. You can play around and turn the axis labels off and use text controls as labels or two different vertical pointers to give the appearance of two separate graphs. Frankly, I usually find it simpler to just have two separate graphs when I want the plots spearated.

[ccurtis]

Dennis,

Many thanks for your help. I thought it might end up being multiple graphs, but I do appreciate the in depth answer for doing a single graph with multiple plots. I was hoping you would give me some detail on doing the single plot and you have provided more than I expected. Will try it out to see which way works best for what I am trying to accomplish. Thank you very much!

Have a Great Day!
Charlie