What is a buffer?

Ok, I think I already know (and use them on a regular basis), but I am wondering what a "buffer" is...maybe an example of one?? I've seen that term all over the place on this site and others, but I've never really sure what is meant by it.

Hold on a sec, answering an email, I'll get to this next.

There ya go!

OG

'Buffer' (in PLC's, computing, etc) generally refers to one of two possible definitions.

1) A temporary holding location for data, which holds a copy or amalgamation of the data. In communications for example, serially, you receive one byte at a time (technically one bit, but we don't look bit-by-bit). In order to assemble an entire message, you move the raw bytes into a separate memory area - a buffer. Once completely assembled, it is typical to move the entire contents of the buffer somewhere to act upon the message, freeing it up for the next incoming message.

2) A complete copy of a set of data, that is acted upon in a program. This is typical with the I/O buffering schemes that are used often on the Logix series processors. You copy all the physical inputs to internal locations in the PLC memory, and use the internal locations for your control process. Similarly, you drive internal tags as outputs, and then copy them at one time to the physical outputs.

There are other definitions, but those should cover most cases with PLC programming.

Exactly what I thought! Sorry for the newbie question, I have just never known what people meant by that term, but, this is something that I do all the time in my programming.