Water Softner Drain to Black PVC 5" with Cap

I have a PVC drain outside for draining pool etc. It is Covered by a Cap that is screwed in when not draining or cleaning filter.

Can i connect my Water Softner Tubing, with an Airgap to the Side of the Outside Drain?
Will it keep the smell out and also allow the water to run into Large Drain outside?

I hope someone has the answer and if more info is required, just ask.
Thanks
Sey

Where is your water softener located? Isn't it anywhere near a drain with a trap in it, such as your washing machine discharge standpipe or a utility sink? Traps are what keep sewer gas from entering a home. I highly doubt that a dishwasher air gap will work for that.
Black plastic drain pipe is ABS, not PVC (different "glue" requirements).
Please give us a little more detail about what you're working with (layout and rough distances), and we'll try to help. (BTW, I am not a pro plumber, just a long-time DIYer, but there are a lot of pro plumbers here who can help you.)
Mike

If the pool drain is a landscape drain , meaning it drains to the street or storm sewer, then you cannot connect a softener to it. If it is a sewer, you could, except that cleanout is not trapped, so there would be an odor, and it seems like a clumsy location to put a softener drain.

The Softner will be located in my garage. (approx 20x24)
If you think of my garage door as being South, the Water Input is SouthEast and that is where I want to locate the Softner.
My closest trap is the Washing Machine and that is in a different room atleast 34feet away(norhtwest).
The Outside ABS drain to sewer is about 4feet from planned location. ( east)
Any Ideas would be appreciated. And any questions will answered as clearly as i can.
thanks sey

I now realize that i can not use the ABS line.
How about a small dry well (5gal or so) to drain the regeneration water into.
I am in the Phoenix Area. Does that sound like a Idea worth executing?
thanks Sey