Programming Proficiency test for potential new hires. Need suggestions/input.

I am a senior controls guy at my company on a new team, and have been put more or less in charge of vetting new controls hires. A colleague and I have already put together an electrical control design test to gauge potential new hires on their ability to read and understand prints, knowledgeably on symbols and good design practices, attention to detail, yadda yadda yadda, with the explicit goal of making the test as brief as possible. We would like to do the same for the programming side, but are having difficulty coming up with a test that would be brief, but could also give us insight as to the ability and experience level of the potential new hire.

So, has anyone run into tests or helped make a test along these lines before? Or could I get some suggestions about things to include in a test.

I am wanting to make the test either platform independent (just basic ladder logic, to be done on paper) or on AB Logix5000.

Ideally the "test" would take less than 15 minutes for even a green programmer. maybe 2 or 3 minutes for someone experienced.

Would like to stick to the more common bits and bobs in ladder logic, the examine off, examine on, coils, latches, timers, maybe counters, but would like to avoid math, gsv's, AOI's, JSR's, and more advanced things as we rarely use them in our line of work.

Ladder only. For whatever reason, my company as a whole avoids any language not ladder like the plague.