Hang on a second, guys. Before we go sell him the Starter Kit (or someone suggests an alternative brand), it sounds o me like he currently has a quote from an Integrator or OEM for the retrofit, and is asking about the feasability of it.
The short answer is, if it's got existing controls, retrofitting is do-able. I've done many retrofits, and usually the biggest problem is the cutover. The machine is currently in production. 24/7? There is a window of opportunity (during a normal plant shutdown, often between Christmas and New Years), but typically 24-36 ours wide, where you have to come in (with a team), cut the wires to the old system, wire in the new, test the I/O, and be back in full production before the end of the window.
Good Coffee is important during these fire-drills.
The fact that it's a Micrologix going in, means that there;s not much I/O. That's helpful. I'm assuming that the Integrator/OEM knows how big the window is.
The key to doing it successfully is TESTING. Since there won't be a real machine to test with, they will have to write code to simulate on. It helps if theres an HMI/SCADA associated with this, so you can "SEE" that the valve that is supposed to open, "actually" does (you can always go by the PLC's LED, but that's tougher).
If there's no HMI, I suggest that Jason insist that the vendor build something reprentative of the machine (I'm remember a post on the old forum, by Goody I think, where that was done, using stuff from around the house.). It doesn't have to pretty, it just has to allow Jason to KNOW that the new system works, before any wire is cut.
Second, project management on both sides is important. Particularly schedule. The FAT should be WEEKS before the installation, not days. Schedules slip. Code is buggy. It has to be 100% done and right prior to installation, or the chance of success drops precipitously.
As for the PLC itself - presumably the vendor knows how much I/O the spaghetti packer machine has, and has sized the PLC accordingly. So it's the right size for the job that is to be asked of it. Will you, tomorrow, ask it to do more? Decide today, because there are limitatins to the amount of I/O it can handle.