>>Good thoughts Lutz and Al. Thanks.
>>
>>I'm ok with backing off on the process side, but I'm still interested in monitoring some temperatures, and displaying an ongoing status for them on my running VFP business program. The answer to this might be in your link Al, but my question now shifts to how do I capture those temperature readings (and I'm still interested in doing this capture without a real PLC in the picture) if the existing process is in place without a PLC. For a sample problem, I'd just like to know how to wire something up, to get an outside temperature to display on my VFP screen in my house. I'll be going through the provided Bastian link (and where it takes me) tomorrow.
>>
>>Bob
>
>Bob,
>
>So you like to do the PLC control and monitoring / supervision on a PC
>
>If you do this asynchronous (The PLC can store records and the PC pulls them later) monitoring could be o.k.
>control -> as others point out a PC is much to vulnerable.
>
>I still prefer to have to PLC on its own (without uplink).
>:)

From a link provided in this thread earlier …

Nate says: PLC’s are doing everything you want, and what people [also] want are complex MES that gather data and display dashboards. that is PC territory.

Robby paraphrases: However, PLCs have caught up and in many cases surpassed those features that were once only available in a PC based control solution and now PLCs are the only way to go. Unless, as Nate mentioned, you are gathering data at the plant level with a data logger such as Historian or a high level plant wide SCADA.

I’m fine with the PC taking on a SCADA like role, and somewhat delayed (with asynchronous access) reporting, is not a problem. I’m still not quite understanding what the hardware pieces look like though. Once that’s clear to me, then I’ll have a base to work from to understand what the software implementation would look like.

A parallel answer for a home application (without a PLC) would be quite useful too.

Bob