hi GUWS,

the SFBs are described in the Step7 online help and in this manual:

System Software for S7-300/400 System and Standard Functions Volume 1 and Volume 2

 The error "1" means:

Communications problems: connection aborted or no logon
With acknowledgment-triggered reporting active: temporary display, if no
display devices support acknowledgment-triggered reporting

Also read the description of the function in the manual or Step7 help. maybe you get a clue what could be the problem,

hope this helps,

regards,