An ABAP program in an R/3 System uses an RFC or CPI-C call to start an ABAP program in an R/2 System on an MVS/VSE host, and exchanges data with this program.

The SAP Gateway builds connections to the R/2 host via LU6.2 using services of the SNA communication subsystem. Several communications requests can be processed via one SAP Gateway.

With this constellation, you must note the following guidelines:

• Using the RFC interface:

• There must be a SAP Gateway in use that supports SNA.
• There must be an SNA communication subsystem.
• The called function must be an ABAP function module, which has the "remote" ID in the function library.

• There must be a SAP Gateway in use that supports SNA.
• There must be an SNA communication subsystem.
• The ABAP target program on the R/2 host must contain the form routine specified in the connect data.
• The calling ABAP program must build the data for the logon to the target system, convert it to EBCDIC and receive the response (possibly a denial) from the target system.
• The side info table TXCOM must be configured in the calling R/3 System. For this, use transaction code SM54.

For details on the configuration of TXCOM, refer to the relevant topic in the following documentation:

• Using the CPI-C interface

• There must be a SAP Gateway in use that supports SNA.
• There must be an SNA communication subsystem.
• The ABAP target program on the R/2 host must contain the form routine specified in the connect data.
• The calling ABAP program must build the data for the logon to the target system, convert it to EBCDIC and receive the response (possibly a denial) from the target system.
• The side info table TXCOM must be configured in the calling R/3 System. For this, use transaction code SM54.

For details on the configuration of TXCOM, refer to the relevant topic in the following documentation:

Once the above requirements have been met, select the target system with the Transaction SM59.

• Using the CPI-C interface