Hello,
 
So I am having a very difficult time understanding how to automate the built-in arpeggiator on the midi section of the ProChannel in Sonar X3 producer.  Online, I have found that if you click and choose 'arpeggiator' in the drop down 'edit filter' in the track lane, then it gives you a list of editable envelope options.  However, I find that in that drop down menu, that arpeggiator is not an option.  There is volume, pan, and mute.  For the Prochannel there is  compressor, eq, tube saturation, and console emulator channel, and any other plugins I have specifically loaded onto that track (reverb, delay, etc.), but no arpeggiator.  If I choose Console Emulator Channel then all I get is an 'enable' option but that does not seem to do anything specific and definitely not what I want to do, which is turn the arpeggiator on and off on a specific track during different parts of the song I writing.  Can somebody please help me?  I'm tearing my hair out on this.

My understanding is that arpeggiator settings are in the Track view, Track Inspector, often found to the left of the tracks. When I look, I see a heading section that shows properties of the clip or track depending on which tab is clicked. Under that there are two columns of settings. The column closest to the tracks begins with knobs for chorus and reverb, then settings for snap to scale, then settings for input quantize, then settings for the arpeggiator. Click on the on/off button next to the "Latch" button to turn it on. Many settings available to work with.
 
Edited to add for clarity: Of course, the arpeggiator is found in the track view of a MIDI track because you are working with MIDI. The ProChannel hosts Audio processing and Audio effects, so no MIDI arpeggiator there.
 
Edited to further add: If you are working with a "simple instrument" track, things get more confusing. A "simple" instrument track has the complexity of combining the MIDI track of notes for the synthesizer to play and the Audio track for the sound from the synthesizer. For the "simple" track, the track inspector defaults to showing the Audio options. A right click on the track number gives a context menu with an option to "split instrument track." Do that, and the now-visible MIDI track has the arpeggiator in the inspector area.

You might find a more productive way by doing it like this...
have you recorded the parts of the arpeggiator to a midi track ?
After they are recorded simply open the piano roll and delete the notes you don't want.
The End...Done.
Or Automate the Mute button, you decide.
 
Im not sure you can Automate the arpeggiator and im not sure there is really any reason to do so.
You can automate the notes once they are laid down.
Its midi data and can be easily edited / removed.

rwheeler, that was the ticket.  Thank you.  

Poking around to figure out possible automation of arpeggiator has been a good learning exercise for me. When I have selected a MIDI track I can open track Automation Lanes by clicking on the zigzag button. Among the automation options, we have an item "arpeggiator" with a sub-menu of multiple parameters that can be automated (Arp source mix, Dur, enable/disable arpeggiator, Flam, Octave, Pitch, Rate, Swing, Vel).
 
However, the Automation Lanes in an Audio track or a "simple instrument" track only show audio parameters to automate (volume, automated mute, pan, PC track EQ settings). Splitting the simple track generates the MIDI track portion with the MIDI automation available, incouding arpeggiator automation.
 
I think the automation applies to the arpeggiator built in to the track inspector. A separate arpeggiator can be  added as a MIDI track effect by right clicking in the effects bin and selecting arpeggiator. At least that is the case in Sonar Platinum.