Using the Solution Manager, open the following address,
http://SOLMAN-HOST:SOLMAN-PORT/smd/AgentAdmin
The address will direct you to the below page and you can get the version of all connected Diagnostic (SMD) agents listed. (The information will be under Agents > Agent Information tab.
Alternatively, go to the below directory (example, for Windows)
C:\usr\sap\DAA\SMDA98\SMDAgent
Open the file named, smdagent.properties and look up the following line (contains the SMD agent version)
/exe/jstartupimpl.jar:lib/patch_7.10.4.1.20120220121517/
