Depth sensing Limit switch

I've been working on a depth sensing aparatus that probes the wood surface and then throws a switch on contact. The SC, 2 command is not clear to me though. I need to turn off and on the read ahead function. I know that sc 0 turns it off and the sc1 turns it on. What I don't know is exactly how SC 2 turns it off temporarily and back on again. My routine works like this I send my z axis down to a depth that is deeper than I need. Then the limit switch is hit and the flow of the program is sent to a subroutine that zeros the z axis and then sends it down to the proper engraving depth. I turned off SC so that the software will read the switch correctly. Then I need to turn it back on just before I start engraving. Can I just use SC,1 or would SC,2 be the right choice?

I played around with these sc commands a bit and discovered that the sc,2 command works like the old sc,1 command. It turns off after each z axis move.