I see these used more often as a distributed I/O unit, such as in breaker, MOD and transformer cabinets. They have several protocols available, as well as SEL logic (latches, counters, math variables). Maybe for a small application you could use one. You can get additional I/O (digital & analog), Voltage & Current, comm cards. There are LED's and pushbuttons available on the front.
If you need a low cost true PLC SEL has the 3505 RTAC which is less than $1000. It does quite a bit for the money, with very limited I/O.
If you have SEL 5030 SW (free to download) you can see what's available in terms of programming logic. I would saw its more like a traditional SEL relay in logic capability than a PLC.
Of course, you can call SEL and they'll send you a loaner and see for yourself.
