if a picture is worth 1000 words ...
Greetings, Eddie,
the approach that rdrast and mmw are recommending is a very common technique which is often called “packing” the data ... here are some examples of how this can be done (there are many more ways than those shown here):
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the basic idea is to take information (examples: the on/off status of bits, the values from timer and counter accumulators, motor speed values, etc.) from various memory locations scattered throughout the PLC processor’s memory, and then “pack” that information into one continuous block of words ... this “block” of words is often called a “communications buffer” ... the advantage to this technique is that each time the HMI (example: RSView, PanelView, etc.) communicates with the PLC processor, only one read is (usually) required ... naturally this helps optimize the communications network traffic and gives faster screen updates and crisper control ...
and to answer your specific questions:
Can I do that on the equipment I'm using? Is that what the N registers are for?
yes, the "fixed" SLC processor will handle this type of programming ...
yes, the N registers can certainly be used for this ... OR ... you can also use the B registers as mmw suggested ...
hint: there is NO difference between a “bit” in the N registers and a “bit” in the B registers ... a “bit” is a “bit” is a “bit” ... and there is NO difference between a "word" in the N registers and a "word" in the B registers ... a "word" is a "word" is a "word" ... the thing that confuses most beginners is that when we work with the N registers, we’re USUALLY dealing with integer values ... in other words with NUMBERS which range somewhere between –32768 and 32767 ...on the other hand, when we’re working with the B registers, we’re USUALLY dealing with the on/off status of something ... (for example: the drilling cycle is in progress, or the grinder head has been all the way down) ...
but ...
there is NO real reason why an integer value (in the range of –32768 to 32767) could not be stored in a B register (for example in word B3:7) ... and there is NO real reason why a bit from an N register (for example N7:0/5) could not be used to mark the on/off status of a machine’s drilling cycle ...
but besides the point that there are no REAL reasons why you can’t “mix things up” by substituting bits from the N registers and bits from the B registers, there are certain “conventions” to ladder logic programming to consider ... people sort of “expect” things to be kept in their “normal” places ... you can write some pretty confusing code by mixing things up in places where they’re not USUALLY found ...
and now on to a related topic ...
secret handshake: the address B3/0 is the address of a “bit” ... the address B3:0 is the address of a “word” made up of sixteen bits ... notice the difference between the “/” (slash) and the “:” (colon) characters ...
the address B3:0/4 is the address of a “bit” (bit number 4) located within a “word” (word B3:0) ...
the address N7:6 is the address of a “word” made up of sixteen bits ... the address N7:3/9 is the address of a “bit” (bit number 9) located within the “word” N7:3 ...
finally ... this might be more than you really wanted to know ... I have a reputation for “over killing” even the most simple topics ... but even if you’re already familiar with all of this, it’s highly likely that someone else will eventually stumble across this information and find it useful ...