Ty McKinney

Hello,
I do not believe the driver supports scanning with the DMM6500. The example you're referencing states it's a DAQ6510 example, which would explain why the error is saying that the command is not supported by the DMM6500. See attached picture for DAQ ONLY capable commands.

Hello Bernhard,
This App note performs a similar operation. This could be a great starting point and to sort out some issues you are having.

Using the Arbitrary Waveform Capabilities of the Series 2600B and Series 2650A System SourceMeter SMU Instruments to Perform Ford EMC Power Cycling Testing | Tektronix

Hello Mishra,
Unfortunately, that series of power supplies cannot be programmed to supply negative voltage. However, if you swap the leads, red lead plugged in to black/negative channel output, and the black lead plugged in to the red/positive channel output, you can supply a negative voltage through your DUT or Device Under Test.

To establish communication between your computer and DMM6500, you will need VISA such as TekVISA, Ni-MAX, or another VISA of your choosing, and a communication protocol of your choosing that is compatible with the DMM6500. 
I will attach the User's Manual below here. See Section 3 to determine which communication protocol you are going to establish.
Model DMM6500 6½-Digit Multimeter User’s Manual | Tektronix

Brian,
Unfortunately, to return the instrument from remote operations mode to local mode, this will require a button press from the front panel.

The only option if you want to use autozero sometimes, but not all of the time during one 500s interval is to swap between config lists as you had mentioned before - I agree with Andrea that every 2s could possibly be too often and will lead to extra time being added.

Swapping config lists seems to work - we set up a trigger model that recalls a config list with azero ON, take 10 readings, switches to azero OFF, takes another 10 readings, and repeats. The resulting data shows that when azero is ON the readings take longer than when azero is OFF. You also would have to consider the time it takes to swap between the config lists. When the swap between azero OFF and ON is performed, the instrument will refresh its reference measurement each time.
Overall consider if the timing delay incurred by the settings swap via various config lists is worth the time saved by not using a zero all of the time.

To take proper 4-Wire resistance measurements with your scan card, the channels must be paired. For example, on a 20-channel card, channels 1-10 can be used as a system channel and 11-20 can be used as the paired channels. CH 1 and 11 will be paired together, 2 and 12, 3 and 13, and so on. See the attached reference manual pages 2-7 through 2-9 and that should supply more in-depth information as well as a schematic of what that configuration would look like.
https://download.tek.com/manual/2701-900-01G_Feb_2016.pdf Model 2701 Ethernet-Based DMM / Data Acquisition System User's Manual

Currently using a Keithley 2701 to read 4-wire resistance in channels 101:105, 2-wire resistance in channels 106:110 and 116:120. In my VI, when passing this list of channels, the VI (Virtual Interface) throws an error. However, when I only use 106:110, 116:120, it works. How do I include the 4-wire measurements in the channel list?

I'll attach a snippet from the 2182A data sheet and post the link to download the datasheet as well as the reference manual below.
The reference manual will have all of the SCPI and operational information you would need for your application.

Datasheet:
https://www.tek.com/en/datasheet/nanovoltmeter-model-2182a

Reference Manual:
Models 2182A Nanovoltmeter User‚s Manual | Tektronix
See section 13 for SCPI command reference. Also, to manipulate speed I would alter your NPLC, delays, filters, etc. to fit your specific needs.

You can definitely control the measurement rate while scanning, you will just have to account for scan rate.