Hello asd;

In the following FAQ, you will find a link to the gsd file for the EM 277, a link to the procedure to insert it in the Profibus master's configuratr files, and a step-by-step guide to configuring a S7-200 CPU (with an attachd EM 277) as a Profibus slave to a S7 master.

How can you communicate data between the S7-200 and the S7-300 via PROFIBUS DP?

https://support.industry.siemens.com/cs/fr/en/view/2615830

 You should open your Profibus slave lists in the Profibus confiurator, normally the EM 277 is already included, if the master is a Siemens PLC. If it is not, use the attached gsd file, taken from the link above.

Hope this helps,

Daniel Chartier