What is RFC and how to create RFC in SAP SM59

• For business applications, it is essential to communicate and exchange information with other systems. SAP has provided a well defined mechanism called RFC (Remote Function Call) to enable this communication.
• RFC Connections in SAP system are used to establish connection with another SAP system or non-SAP system.
• SM59 transaction code is used to create RFC (Remote Function Call) connection.
• There are different types of RFC connections available in SM59 transaction code.

We mainly used to create 2 types of connections in SM59.

1. ABAP Connections (Type 3)
2. TCP/IP connections (Type T) 

STEPS TO CREATE RFC CONNECTION

1. Select 'Create' icon
2. Provide RFC connection details

• RFC Destination: RFC connection name
• Connection Type: For example 3 or T
• Description: Any short description, purpose of the connection

3. Save the RFC connection

NOTE:

Once the RFC connection is saved, it will take us to the tab 'Technical Settings'.

Technical Settings

• Load balancing

Select Yes, if load balancing is configured in system, else

Select No

• Target host: Either Hostname or IP address of the target system
• System Number: System number of the target SAP system

There are 5 tabs available, in which it is required to fill few of the target system details.

1. Administration:

No input is allowed. It just provides the information on who created/modified the RFC and also the corresponding Date/time.

2. Technical Settings: As explained above

3. Logon and Security:

• Language: Target system language, most of the time it's EN
• Client: Target system client number 
• User ID and Password: User details of Target system

NOTE: 

• In general, RFC users can be of any user type
• For security reasons, it is recommended to use only system users for RFC communications, to avoid access to dialog processes.

• Security options:

• Default setting for 'Trusted System' is 'No'.
• If we need the Trusted RFC connection, select 'Trusted System' as 'Yes'.
• This means, the trusted system doesn't need a password to connect with trusting system
• Trusted system = calling system = Source system
• Trusting system = called system = Target system

Some of the features of this option:

• It provides Cross-system SSO (Single-Sign-On) capability
• Password does not need to be sent across the network
• User-specific logon details of the calling system is checked
• Time-out mechanism for the logon data prevents mishandling of logon data

4. MDMP & Unicode:

• On a Non-Unicode system, the settings under this tab are disabled and no changes are allowed.
• This setting is valid only on an UNICODE system, we have to specify the Unicode settings.

NOTE:

If the SAP system is upgraded from Non-Unicode to Unicode, we need to change the communication type to 'Unicode' on all the applicable RFC connections.

5. Special Options:

This option is very rarely used.  For example

• We can activate options for a trace and slow RFC connections.
• To define qRFC

TESTING THE RFC CONNECTION

• Once all the necessary settings are made and the RFC connection is saved, final step is to make sure the connection is established successfully.
• There are 3 types of connection tests are available.

1. Connection test:    

This is the most important. This test is just to check if the calling system is able to reach the remote system. This authenticates the information provided in the RFC connection for target system.

• If the connection is successful, it displays the table with response times. Else
• An error will be displayed with the reason, and troubleshoot is required to fix the issue.

2. Authorization Test:

This test validates the Client, User ID and Password (provided under 'logon and security' tab for the target system).

• If the Authorization test is successful, it displays the table with response times. Else
• An error will be displayed with the reason, and troubleshoot is required to fix the issue (check the logon details and authorizations)

3. Unicode Test:

• This checks if the Target system is an Unicode system or not

RELATED LINKS:

[1] How to change the TMS RFC in SM59

[2] Important RFC tables and reports like RFCDES

[3] RFC Communication types in SAP

[4] Different types of RFC connections

[5] SAP user types