Hello Anil,
The addresses of the EXMs have no practical meaning for the FM458 programmer. The FM458 uses the periphal_adresses to access the EXMs (The FM uses the LE-Bus an not the backplane to access the EXMs. The EXM mainly only gets power supply

from the S7-Rach backplane.).

Communication S7-CPU -- FM458:
For general information look here (chaper 4.3)
If you use data sets (virtual connections) I have one tip:

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How to follow virtual connections?

- while compiling D7-SYS will gernerate a MAP-Listing, this file includes some additional informations about virtual connections. In the compiling-log there is a line like this:
"I: CPU-MAP-Listing C:\PROGRAM FILES\SIEMENS\STEP7\EXAMPLES\D7-FM458-BASIC-PROG\ES_LOC\3\gen\pnmap.pro wurde erzeugt."
- copy the italic part and press <Win><R>,
- enter "notepad " and <STRG><V> and press enter
- the file "C:\PROGRAM FILES\SIEMENS\STEP7\EXAMPLES\D7-FM458-BASIC-PROG\ES_LOC\3\gen\pnmap.pro" is opened in notepad.

look for lines like that (I used a example project, see picture:
communication programming - sender direction (virtual connections)</p><p>  sender      sender func. block                        generator   name    Tx  connection                     length Nr. Tx  connector</p><p>  SEND11  T2  Communication.11.CRT             6  0000  T1  Communication.16.Y             2  (INT)                                                   0001  T1  Communication.18.Y             2  (INT)                                                   0002  T1  Communication.20.Y             2  (INT)   SEND12  T2  Communication.13.CRT            12  0001  T1  Communication.24.Y             4  (DINT)                                                   0002  T1  Communication.25.Y             4  (DINT)                                                   0003  T1  Communication.26.Y             4  (DINT) ================================================================================</p><p>communication programming - receiving direction  (virtual connections)</p><p>  receiver    receiver func. block                      target/user   name    Tx  connection                     length Nr. Tx  connector</p><p>  RECV11  T2  Communication.12.CRR             6  0000  T1  Communication.15.X             2  (INT)                                                   0001  T1  Communication.17.X             2  (INT)                                                   0002  T1  Communication.19.X             2  (INT)   RECV12  T2  Communication.14.CRR            12  0001  T1  Communication.21.X             4  (DINT)                                                   0002  T1  Communication.22.X             4  (DINT)                                                   0003  T1  Communication.23.X             4  (DINT) ================================================================================

This should help you to follow virtual connections.

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