I'd be looking at a 1769-L16ER-BB1B. Uses Logix 5000 v20 and upwards, has it's own power supply, has onboard digital I/O, and the expansion cards for it are 1734 point i/o, so much cheaper than your 1769 compact i/o. Or you could even look at one of the 1769-L24ER-...can't remember the rest of the part number offhand but it also has analog inputs/analog outputs/high speed counters all onboard.
Might be harder to pick up secondhand (i.e. cheap) but gives you a much neater solution that, especially in the case of the L16, is much cheaper to expand.
Might be harder to pick up secondhand (i.e. cheap) but gives you a much neater solution that, especially in the case of the L16, is much cheaper to expand.