PSoC Designer 5.1 Service Pack 2.1 is available through the CyInstaller update manager or located at www.cypress.com/go/psocdesigner.
The PSoC Designer 5.1 SP2.1 is a rapid release to address the following issues:
• Project update wizard will now retain Pin State selections for updated projects.
• CSD2X user module revision to address failures when upgrading from older revisions.
• Support for the CyInstaller v2.2
• PSoC Designer Installer update to workaround the Microsoft Windows Installer 4.5+ defect.
PSoC Designer 5.1 SP2.1 requires the latest version of PSoC Programmer located through your CyInstaller update manager or located at www.cypress.com/go/psocprogrammer .
i am using 5.2 SP1 ， it did not work sometimes
this will help a lot！