AB remote I/O

lawebster wrote:


BTR is Block Transfer Read and BTW is Block Transfer Write. The information
that will tell you what the bits in the five integers mean will be in the
manual that deals with the particular card. So, look in the 1794 manual and
look up the command words and status words for it. These are the ones you
use BTR and BTW to transfer from or to the card.

The 1794 manual is on-line at Rockwell's site.

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I had downloaded and read all manuals concerning the 1794 mods and they
talk about the Data File but nothing about the Control Block. I have
gathered from the Instruction Help for BTR,BTW that the bits 07-15 are
status and 00-06 store the modules address but this is only word #1.
What are the other 4 words of data for? Is this something I need to
program or is it more instruction status bits? Just not sure what I
need to put in these other 4 data files.
Am I just not looking at this correct?

Each word of the part of the control block you're referring to is module
specific. If you're using RSLogix 5 the module setup dialogue box will set
those words for you. Use the IO configuration that the RSLogix provides for
you. It's in the project tree. Install the chassis in the program, and
choose the ASB module you're using to communicate with the flex IO rack.
You'll need to provide a starting Rack and Group number as well as the
number of slots in the chassis. Once that's done you can pick which module
you're using and which slot it is in simply by doublr clicking a vacant slot
in the chassis. At that point you configure the model and the appropriate
values are written to the words in the control block you're concerned about.
It's done for you.

I assumed (I know, I know) that you're using RSLogix5. If you're still using
ICOM or 6200 software gooooood luuuuuck :)

Ursa Major wrote:


To add to that answer I would need to look at the books at work. It will be
after the weekend as tomorrow is a busy day in operations.

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Forth based HIDECS Consultancy .....<http://www.amleth.demon.co.uk/>
Mob: +44 (0)7811-639972
Tel: +44 (0)1235-811095
Going Forth Safely ..... EBA. www.electric-boat-association.org.uk..
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One other thing I forget to mention. Don't try to manually create the
BTW/BTR rungs yourself. Once you've configured the module inside the module
configuration dialog box click the button "Insert Ladder Rungs". Let the
software Autopick and create the data files needed for the block transfer
instructions. Then you'll choose which ladder file to create the rungs in.
If you have an existing block transfer ladder file tell the software to put
it at the end of the file. If not tell the software to create a new file.
It's a fairly intuitive process and pretty easy to accomplish.

I remember the first time I had to add a 1771-IFE module (Analog Input) to a
spare slot in an existing rack using the older software that AB provided.
Took me quite a while to complete what I thought would be a fairly simple
task. It's much easier these days. Let us know how you make out...

Exactly which PLC-5 processor and what programming software are you using?
Any fairly modern PLC-5 (past 15 years or so) will also use the BT data type
for the control block, which makes your issue moot, as the sub-elements will
be named rather than numbered. I will nonetheless do a bit of research on
your behalf.

Enhanced PLC5/20 16,384K Mem.
Also one thing I didn't mention is that this is an existing system and
I need to add to it. There is existing ladder logic using BTR/BTW
instructions.

Thanks for the info.

RSLogix 5 software

You may find the answer you need in AB manual 1785-6.1, page 15-5,
available at www.ab.com.

word 0 - status bits
word 1 - requested word count
word 3 - transmitted word count
word 4 - File type-number
word 5 - element number

I provide this information as a direct answer to your direct question.

Bear in mind however, that, as others have pointed out, the need to
know this information proves that you are on the wrong track, unless
you are trying to reverse engineer an old program. The best way to add
new block transfers is to use the configurator accessible from within
the "I/O Configuration" folder in the project window of RSLogix 5, and
to use an element of the BT data type as the control block. There is
really no reason at all to be concerned with how the control block is
organized.

It doesn't matter whether he's using a "Classic" processor (5/25 or below)
or enhanced processor. With RSLogix5 you do not have to manually configure
the data file for the BTW/BTR. You do not have to manually configure the
control block words either. That's data that RSLogix automatically
configures and is used by the processor to complete the transfers.  There is
no reason to fart around with them. During the module addition in the IO
config all data written to the appropriate data block is done for you. If
it's attached to an older processor the appropriate integer words are
automatically written. If it's one of the newer processors the BT (block
transfer data types) are automatically written. Both cases are contingent on
letting the software insert the ladder rungs containing the block transfers,
however.  In older versions of the software I/O was a pain in the ass. Not
really the case anymore. Hours spent perusing a module specific manual
looking to set individual bits or entire words in a BTW data block are long
gone. You could spend the hours needed to do it the manual way like the old
days, but I don't want to lose any more hair. I can't afford it any more...

RSLogix5 is natively aware of all 1794 I/O. You pick the module you want to
install from a list inside the software. Every module is listed once you
specify Flex IO in the "Add Chassis" dialog box. Once the module is
installed the software knows how to handle the BTW/BTR pair for the specific
module.

Thanks to everyone for the info, it is apprecitated