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Old July 31st, 2004, 01:02 PM   #1
Eddie22
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RSView32 Tag Database Addresses

Hi. In my RSView32 tag database my input and output addresses won't take properly. The tag monitor shows their status as ERROR. My T4 timer and B3 aux addresses work fine. To get around the problem I attached a bunch of B3 OTE's to the inputs and outputs and put those
addresses in the tag database, but obviously this is wasting a lot of memory, as well as slowing things down.

Tag address T4:0/TT shows VALID status, tag addresses I:0/0 or O:0/0 show ERROR status in the tag monitor window. I:0.0/0 doesn't work either.

Just starting out with this stuff. Thanks for the help!

Using:
AB SLC 500 1774-L30A
RSView32 1500 6.10.16
RSLogix 500 4.00.00.60
RSlinx 2.00.97.30
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Old July 31st, 2004, 04:19 PM   #2
Ron Beaufort
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take a look at:

RSView32 User's Manual

start on page D-12 [Adobe Reader page 714 of 772] ... this should answer all of your questions ...
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Old August 1st, 2004, 10:52 AM   #3
Ron Beaufort
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sorry ... it looks like "you can't get there from here" ...

Eddie,

after I made my last post I went home to cut the grass ... halfway through the front yard, it suddenly occurred to me that some of the addresses that you had reported as unworkable were EXACTLY the addresses that the book recommended ...

I don't have a "fixed" SLC at home ... but I do have a MicroLogix1000 which SHOULD use the same addressing scheme ... I set this one up and tried the RSView book's recommended addressing ... it doesn't work ... I get the same results that you reported ... I also tried every other reasonable syntax that I could come up with ... nothing that I tried works at all ... specifically, the inputs and outputs show up as "error" on the tagbase monitor ...


next I set up an SLC-5/04 ... this one SHOULD use the book's "enhanced" addressing scheme ... this one works just fine ... specifically, the inputs and outputs show up as "valid" on the tagbase monitor ...

going further ... when I read the book's recommended addressing for "enhanced" SLC's (example: SLC-5/04) the syntax is EXACTLY the same as the recommended addressing for the "fixed" systems ... personally I think that the guys writing the book made a "cut and paste" error ... I'd be willing to bet pocket change that RSView can't even access the "fixed" SLC's input and output tables at all ... but the "enhanced" processors seem ok ...

as near as I've been able to figure out, your "use-a-B3-internal-flag-bit" is probably the best workaround for your situation ...

sorry for the bum steer ...
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Last edited by Ron Beaufort; August 1st, 2004 at 11:00 AM.
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Old August 1st, 2004, 11:28 AM   #4
Bob O
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FYI

I was able to get I:0/0 and O:0/0 on a MicroLogix 1000 to show valid, but on my 1500 wtih 3 expansion I/O I tried I:4/0 and it came back error. Is there something about if the address isn't in the controllers data tables this may cause an error.
FYI-I have never messed with a fixed 500.

Thanks,
Bob O.
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Old August 2nd, 2004, 04:20 AM   #5
rdrast
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I know this isn't much help, but I have found it to be much better to copy physical I/O to internal memory on the CPU before trying to read them with any DDE/OPC server.

MicroLogix and SLC's do not like to have their I/O tables accessed directly for some reason. I've never actually looked into why, as I normally pack/buffer the information before sending it to an HMI.
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Old August 2nd, 2004, 07:19 PM   #6
Lancie1
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rdrast,

I agree. I have NEVER even tried using any Input or Output address directly in RSView as a TAG, so I couldn't have told you whether it would work or not. I didn't know why at first...maybe that is the way I was shown by somebody back in the Dark Ages...

I always want total control over what RSView sees, so I use an internal relay buffer, B3 or similar. That way, if for some reason I want to insert another condition on the rung, if is very easy and I don't have to redo my RSView TAGS. Also, I like being able to see the Input and Output values in the ladder logic. If you make it a direct TAG, and it is not used except by RSView, then you have to go to the Data Tables to see what is going on.
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Old August 3rd, 2004, 08:52 AM   #7
Eddie22
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Thank you

Thanks to everyone for the help. All the posts made sense after thinking about them. One thing I didn't understand was: "I know this isn't much help, but I have found it to be much better to copy physical I/O to internal memory on the CPU before trying to read them with any DDE/OPC server. --rdrast" Can I do that on the equipment I'm using? Is that what the N registers are for?
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Old August 3rd, 2004, 09:31 AM   #8
mmw
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I think that rdrast is recommending that you do exactly what you are doing ... transfer your real I/O to internal bits. Using B3 bits will work fine. Yes, you could use N (integer) words to accomplish the same task (you must specify the address of the internal OTE to the bit level, like N7:0/0 or N7:12/15)
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Old August 3rd, 2004, 10:58 AM   #9
Ron Beaufort
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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):

[attachment]

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 processors 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:

Quote:
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, were USUALLY dealing with integer values ... in other words with NUMBERS which range somewhere between 32768 and 32767 ...on the other hand, when were working with the B registers, were 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 machines drilling cycle ...

but besides the point that there are no REAL reasons why you cant 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 theyre 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 youre already familiar with all of this, its highly likely that someone else will eventually stumble across this information and find it useful ...
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Last edited by Ron Beaufort; August 3rd, 2004 at 11:18 AM.
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