Micrologix 1100 modbus data mapping.

Hello

I am very new to PLC's and know even less about Modbus. I am writing a program for a AB ML1100 on a Modbus network.I am using RSlogix 500.Can anyone please help explain or even have a small example of ladder logic on how the modbus data tables or mapped to the particular I/O in the plc program.I also I will need to read and write to several interger files for my analog signal controls,to be able to set the upper and lower on and off limits remotely.the ML1100 will be set up as a slave primarly as a data collector to be used in a remote Scada program.
thank you in advance
ggsmith

Modbus

I'm not nearly as good as the majority of the others on this site, but I might be able to help.
You could download this:
http://literature.rockwellautomation.com/idc/groups/literature/documents/um/ag-um008_-en-p.pdf
This file is about 10mb in size but it may help.
It covers more than just the 1100.
Somewhere around page 3-46 it covers Modbus Protocol.

My company is using some modbus protocols with 1200's, slc's, & some other brand equipment. In the 1200, which is a slave (I think the 1100 will be very similar in this regard) We're mapping all i/o we want to use with our SCADA to the N10 File. The i/o we want to read is put in the n10:0 to about n10:63 (pump status, flows, levels, ETM's, etc). The data we want to write
we're getting from n10:65 to n10:76 (setpoints, pump controls, etc).
We basically read 63 holding registers & write to 12.
In Modbus slave config in the PLC we're using the 4XXXX (holding registers) option with a value of 10 (for file N10).
In the Master PLC (SLC 5/05 with a Prosoft Modbus card)we're sending a function code "3" (read holding registers) with a size of "63" to the slave, & put the info into a file, say n12, starting at n12:0.
Then we're sending a code of "16" (write multiple holding registers) with a size of "12" to the slave & get the info to send from n12, starting at n12:65.
Basically all the info in the slave from n10:0 to n10:63 is now in
the master from n12:0 to n12:63 & all the info we wrote from our
SCADA to the master n12:65 to n12:76 is now in the slave n10:65 to
n10:76.
Sorry I drew this out so much, but the PDF file I mentioned above probably explains it way better than I can.
Hope this helps & best of luck.

Oops

Through my babbling I forgot something.
Just a simple example....
Misro 1200 with an Analog input card attached.
In the slave plc we may have a pump 1 fail input (I:0/0)
Pump 2 fail input (I:0/1)
Flow Input (I:1.0)
In the Ladder we're just using I:0/0 as input (XIC)& n10:1/0 as the output (OTE) on the rung.
I:0/1 would be n10:1/1.
For the the Analog Input we're using a SCP Statement with the input
as I:1.0 & the out as n10:10.

From the SCADA we look at the master PLC's info, with what I said before:
Pump 1 fail would be n12:1/0
Pump 2 fail would be n12:1/1
The Flow would be n12:10.

Forgot this part as well,
In the slave PLC (going with what I stated above):
N10:1/0 would be in modbus "40001:1"
n10:1/1 would be in modbus "40001:2"
n10:10 would be in modbus "40010"
In the Master:
n12:1/0 would also be "40001:1"
n12:1/1 would also be "40001:2"
n12:10 would also be "40010"
Best I can remenber, Modbus starts at "40001"