Passing text message from external system to an RFC EXCEPTION

In function module CREDIT_CARD_SETTLEMENT the following DYNAMIC function module call exists:

• ------ Send items for settlement to a RFC function -------------------

CALL FUNCTION l_fnset

DESTINATION l_rfcset

EXPORTING i_ccseth = i_ccseth

TABLES t_settab = t_settab

t_setexd_h = t_setexd_h

t_setexd_i = t_setexd_i

EXCEPTIONS system_failure = 01 MESSAGE rfc_msg_text

communication_failure = 02 MESSAGE rfc_msg_text

call_function_not_found = 03.

This is the code which calls an external credit card application server. I'm trying to figure out how, on the server side, I can return a message into the rfc_msg_text variable on the system_failure or communication_failure EXCEPTIONS.

I’ve found several examples of this construct in ABAP code in the SAP side – but I can’t for the life of me find anything that shows how to set this up in our external server.

There are several SAP function modules like RFC_PING that have similar constructs – but I can’t see the compiled C code to tell what command to use to fill in that text. I can raise the exception, just not fill in the text.

Any ideas?