Is your variable data in an array? If so, you can create another array with the same number of indicies with all the values the same as the reference value. Then wire the 2 arrays into a Build Array function, the ouput of this then feeds the waveform graph.

Wheels within wheels / In a spiral array
A pattern so grand / And complex
Time after time / We lose sight of the way
Our causes can't see / Their effects.

Thanks a lot for the reply.
I wanted to plot data (neuromuscular data) from a DAQ card and wanted it to match a target profile or desired signal.

http://forums.ni.com/attachments/ni/170/101531/1/General%20Data%20Collection.VI

Can some one please look at the General Data Collection.vi file an suggest me how can i add my reference signal just before the sweep chart( i guess for cluster # 2).

Thanks,
Ram

Span3D:

I looks like the properties of the sweep chart has set it up to break out each data stream in the bundle into it's own graph. Maybe a simpler solution is to use independant graphs for each DAQ channel and add your profile data into each graph plot by bundling it into a cluster with your data. Then pass that bundle to the graph.

I really need to learn how to post images and file links on this board. Trying to explain a graphical language in textual terms can sometimes be difficult :)

Wheels within wheels / In a spiral array
A pattern so grand / And complex
Time after time / We lose sight of the way
Our causes can't see / Their effects.