Creating RFC Users (SAP ECC) 
To enable communication between the SAP ERP back-end system and other SAP systems, you have to create an RFC user in the SAP ERP system.
The RFC user in the application client enables multiple RFC connections. Skip this activity if an RFC user has already been created.
Procedure
Logon to the SAP ECC system.
Access the activity using one of the following navigation options:
Call transaction code SU01.
In the SAP ERP GUI, choose
Tools
Administration User Maintenance
Users 
.
In the User field, enter CRM2ERP.
Choose Create (F8).
On the Maintain User screen, enter the following data in the tab entry screens:
On the Address tab page, enter the following:
Last Name: CRM2ERP
Function: <your function>
On the Logon Data tab page, enter the following:
User Type: Communication Data
Password: <your password>
On the Defaults tab page, enter the following:
Logon Language: EN
On the Profiles tab page, enter the following:
Profile: SAP_ALL and SAP_NEW
Save your entries (Ctrl + S).
Note
The CRM2ERP user has the profiles SAP_ALL and SAP_NEW assigned, which gives him full authorization rights. If this authorization is not applicable to your project you can restrict the rights of this user according to SAP Note 0338537.