Any check on control for lowest Z position?

Hello all, I'm pretty green when it comes to CNC machining. I'm trying to error check a program after transferring a large surfacing op (4MB) via RS232 (first time). After a couple glitches during my transfer I'm worried about a possible data transfer error crashing my machine. Even more butt clenching because I'm using a rather expensive NSK electric spindle to run a 1/16" ball end mill. I've tried using the graphics mode but I'm not entirely certain how to decipher the z axis info. Plus it takes a VERY long time to run through all that code. Is there any other way to identify the minimum Z position throughout the program(in control). I'm confident of the CAM and post prior to transfer.

Thanks for any help!
Brian

2006 Haas Mini mill