Design guidelines needed

Hi Friends;
Hope all are fine. I want to design a ESD system of compressor station. I am confusing to select the PLC which i used.
I visist the market i found AB SLC100 and S5 plc but software required to programme and communicate with laptop is not available.
I require 15 inputs and 6 outputs. Voltage level is 24 VDC both input and output.
Please guide me which i use and able to communicate with it?
Please suggest me the Cheapest one.
Thanks

Compressor station for what - compressed air flammable gases, cryogenic all have differing criteria and safety concerns.

Buy cheap - well you get what you pay for - OR - marry in haste repent at leisure.

Low initial cost seems good but I think you should consider
1. Life cycle cost
2. Local support
3. Will the low cost outfit be around in 10 years and still support what you bought?

Think I would allow for a few more inputs and outputs - there is always six months later "if we had just thought of this ,,,,,,,,,, and done that we would be better off"
Dan Bentler