so who's this "dummy" that you've run into? ...
Greetings Jeff ...
when Allen-Bradley uses CIP it generally stands for "Communication and Information Protocol" ...
for comparison, here are some other common protocols:
DH+ ... DH-485 ... DF1 ... and now we have CIP ...
quick BASIC idea: think of it as a network language especially adapted for the ControlLogix platform ...
as for your next question – about "What's an Instance" ...
BASIC idea: look at it as part of an OUTLINE format (as for a high-school term paper) ... for example:
I. Roman numeral one (for main heading)
A. Capital letter (next subordinate heading)
1. Arabic number (next subordinate heading) ...
the SAME THING just said another way:
I. Top level
A. Dig a little deeper
1. Dig deeper still
and now the SAME THING in Allen-Bradley talk:
I. Class Name
A. Instance Name
1. Attribute Name
so ... in GENERAL terms, when you see the terms Class, Instance, and Attribute those USUALLY are efforts (for better or for worse) to set up an orderly format of information ...
survival tip:
try the following experiments in RSLogix5000 – don’t forget to use the pull-down selectors to see what's available for each entry ...
first put in a simple GSV rung ... notice that if you select "Controller" for the CLASS NAME, the software will skip right over the INSTANCE NAME ... that's because you don't NEED an INSTANCE NAME – because there is only ONE "Controller" that the GSV could access ...
now select "Program" for the CLASS NAME ... this time the software will allow you to choose from all of the available Programs in your project ... here you NEED an INSTANCE NAME because there could be several "programs" from which to select ...
major "big picture" idea in simplest terms:
I. Class name = start digging here ...
A. Instance name = dig deeper here ...
1. Attribute name = dig even deeper here ...
now if this "general idea" stuff doesn't fully answer your question, how about giving us a screen shot (or just more detail) about WHERE you're running across this particular reference to an "Instance" ... probably one size does NOT fit all ...