Follow these steps
SAP XI
1) RFC Destination (SM59)
a) Choose create.
b) Specify the name of the RFC destination
c) Select connection type as 3 and save
d) In the technical settings tab enter the details SAP SID/URL and system number#.
e) Enter the Gateway host as same details above SID/URL.
f) Gateway service is 3300+system number#.
g) In the Logon /Security tab, enter the client user & Password details of Destination system.
h) Test the connection and remote logon.
2) Create Port (IDX1)
a) Select create new button
b) Enter the port name as SAP+SID (The starting char should be SAP)
c) Enter the destination client.
d) Enter the RFC Destination created in SAP R/3 towards other system.
e) Save
3) Load Meta Data for IDOC (IDX2)
a) Create new
b) IDOC Message Type
c) Enter port created in IDX1.
SAP R/3
1) RFC Destination (SM59)
a) Choose create.
b) Specify the name of the RFC destination
c) Select connection type as 3 and save
d) In the technical settings tab enter the details SAP SID/URL and system number#.
e) Enter the Gateway host as same details above SID/URL.
f) Gateway service is 3300+system number#.
g) In the Logon /Security tab, enter the client user & Password details of Destination system.
h) Test the connection and remote logon.
2) Create Port (We21)
a) First Select Transactional RFC and then click create button
b) Enter the destination port name as SAP+SID (The starting char should be SAP)
c) Enter the destination client.
d) Enter the RFC Destination created in SAP R/3 towards other system.
e) Save
3) Create Partner Profile (WE20)
a) Create New
b) Create the Partner no. name as same the logical system name of the destination system.
c) Select Partner type LS
d) Enter details for Type: US/USER, Agent, and Lang.
e) Click on the + button to select the message type.
f) Select Partner no. and LS which ever create above.
g) Select Message type
h) Select Process code related to the Message type.
I) save.
In SLD – System Landscape Directory
TS for R/3 (Logical system):-Assign the client name created in R/3 as Logical system Name.
Ts for Third Party (Logical system):-
BS for SAP R/3 (Logical system):- Assign the client name created in R/3 as Logical system Name.
BS for Third Party (Logical system):-Enter the XI logical system name.
In Transaction SALE
Define and Assign the logical system name.
after these settings
go to the Business System .
In the menu
go to servive then adapter specific identifiers and check wether the settings are right
Hope this is helpful