You buy a module and an 8 point or 12 point terminal block for each of the slots, so to add you just buy a card and a terminal and clip it in.
Way easier for a first timer to put a point rack together, but not a seasoned flex user. Have had people not push the flex module all the way into its base on one side.
The 1734-IB8 has no terminals for +24v nor 0V, so you have to either:
- buy a point to field distribution module,
- buy 2* IB4
- buy 4* ib2
- land to terminals and daisy chain your 24V.
Point IO is a bargain compared to flex io, ask your distributor for a costed BOM of that point rack and the same (or higher) io count flex rack. Unless he is the sensitive type who might not take kindly to you investigating cheaper io options than his flex cash cow, in which case find the list prices. The part numbers you can't see are those 8 point Terminal blocks which I think are 1734-tbs for the two piece, or 1734-tops for the one piece.
Maybe the Analog resolution is better on flex, I can't recall.
If you can afford the expense, and think your machine supplier is capable of bespoke control systems, standardisation is a nice thing for maintenance and purchasing. 5s and all that.