HELP - adding flex i/o modules

hello everyone, i am trying to get a grasp on remote i/o and learn how addresses are assigned.

We have a weld cell with 3 nachi robots, 1 panelview 550, and 3 seperate racks of flex i/o modules all linked with blue hose and go back to a scanner card on the plc (5/03).

Due to bad parts getting out the door we have to add more sensors to make it pretty much idiot proof. Problem is i have used up all the spares left available to me.

In the section in question..
We have a osalotor turntable with 2 sides - a,b , on each side is a panel which houses a bank of flex i/o modules with their own power supply and linked by blue hose. 4 modules per side, 2 16pt input and 2 16pt output.- 8 total

Currently they are addressed side a - input module - I:1.20/0-15
input module - I:1.21/0-15
outp module - O:1.22/0-15
outp module - O:1.23/0-15
side b - input module - I:1.24/0-15
input module - I:1.25/0-15
outp module - O:1.26/0-15
outp module - O:1.27/0-15

I have purchased 2 terminal blocks and 2 8pt input modules that i need to add on, 1 on each side of the table.

side b i am guessing would just continue on with the pattern and be I:1.28/0-7 but if i add a module to side a what would happen?
would everything get bumped down.

is there someone out there that can give me some advise on the best way to go about this? the last thing i want to do is get into readdressing all those i/o. It is a huge program close to 9000 words of memory used in the plc.

thanks,
mark

Using RIO with an SLC-500 scanner brings together the technology of 1979 with the marketing of 1995... today !

The addresses you have listed indicate that you are using "Single Slot Addressing", which is the default method with 1794-ASB RIO adapters for FLEX I/O. As you have seen, each slot takes up 1 Word of Input data table, and 1 slot of Output data table. This is true even if the module only has all Inputs or all Outputs.

As you have also observed, because the two adapters are using adjacent memory addresses, you can't add a module to Adapter A without overlapping Adapter B. There's no way to "skip" over the Adapter B addresses.

You're not going to get this done without a little search-and-replace. RSLogix 500 makes that relatively painless, but you're in for a little keyboard labor, and probably some wire markers.

(continued)

If you tried to "bump down" the Adapter B addresses, they need to move "1/4 Rack", also called "2 Groups", also called "2 Words". Trust me, it confuses even experts.

Right now, Adapter B is addressed starting at "Rack 3, Group 0". Starting it at "Rack 3, Group 2" means that Adapter B would span the memory x1.26 - x1.29.

With the added module, that would take up word x1.30, but would reserve x1.31 as well.... which means no modules could be added to anything else in the system.

You would have to re-label and re-address all the I/O points on Adapter B.

(continued further)

Here's another approach to conserve memory and reduce the number of wiring label changes.

Instead of "Standard" (aka "1-Slot") addressing, use Compact Addressing. Compact Addressing alternates the positions of Input and Output modules, and does not "waste" I/O image space.

In Adapter A, arrange the modules

16 In
16 Out
16 In
16 Out
8 In

If you then change to Compact Addressing, only the Ouput modules will need to be readdressed. The addressing will be as follows:

I:1.20
O:1.20
I:1.21
O:1.21
I:1.22

Adapter B could do the same thing, which would address those modules as:

I:1.24
O:1.24
I:1.25
O:1.25
I:1.26

This approach allows for futher expansion of Adapters A and B, and allows that last "1/2 Rack" of addressing space to remain vacant. It does involve moving the wiring bases around, and changing DIP switches, but it means you only have to re-label 4 Output modules.

Make absolutely certain that you have the correct 1794-ASB adapter module user manual. Some of the switch assignments changed in Series E and you need the latest book to get them right.

thanks for your input ken.

i started to see the grim picture as i was surfing through
allen bradley's manuals site.

i like that compact addressing idea, i will have to do some more
research into it before i jump in.

thanks
mark

London, Ontario

One of my favorire places...

Wish I was hangin' out at the Locomotive Plant, long about now.....

regards.....casey

i wish i was too casey..making the big bucks..

ken..

i have been doing some more research on compact addressing,
the manual says there has to be an equal number of input to ouput modules, the example you showed has 3 input to only 2 output, will it still work?

also in the manual it says you can go either 8pt or 16pt compact, one or the other, it makes reference to putting a 32pt in a 16pt configuration and it just uses the first 16pt of the 32pt module, but i cannot find an example of putting a lower 8pt into a 16pt configuration, will this also work?

i did some in depth exploring into the cell last night and found all 32 words of memory for the scanner card are used up. When i finally got the standard vs. compact vs. complimentary theroys down i was able to go into the i/o data table and find where everything was.
the standard way wasted alot of valuable i/o space that i thought i still had.

thanks for your help
mark.

casey..go london knights !!!

Yes, you can use an 8-point module in conjunction with 16-point modules. It will be addressed with the lower 8 bits of the data Word allocated to it.

Also yes, you can use an I/O/I/O/I arrangement with Compact addressing. If you added another module, it would have to be an Output module.

ken

i checked the rev number on the 1794-asb and it is a D
will the 1794-asb/e manual work for the d seris?
and is the d seris capable of handling compact addressing?
i added some autocad files of what i plan to do.

mark

The user manual for 1794-ASB/E covers all the previous versions, too.

The major change with Series E was support for some specialty modules and for 32-point modules.

Compact Addressing has been in the 1794 product for a long time, I think since the beginning.

I think that "compact addressing" is also known as "2-slot addressing". If you see 2-slot addressing mentioned in one of the manuals, then you know what it means.

Things to do in London while at the Locomotive plant...

1). Take poloroids on new locomotives and smuggle out of plant. Get one published before unit leaves plant.

2). Go downtown, and try to stay out of trouble.

3). Go to motel, watch curling on tv.


Oh yeah, flip on the tube, watch a little (4-5 hours) of Curling. Man, the women's teams up there puts us flatlanders to shame. Years ago, when I was in high school, I was HOT on the ice, but nothing like some of them ladies.

I could handle the cold a little better 35 years ago, too!

regards.....casey

FORMER Waltham Curling Club hotshot, who now belly flops half the time and lands on buttocks rest of time when throwing a stone. I only fall once or twice a sweeping, but I am top heavy.