This document illustrates multiple ways to identify multiple SCADA systems.
You can download it from the following link: https://packetstormsecurity.com/files/download/119727/scada-googledorks-121227101926-phpapp01.pdf
Source: https://packetstormsecurity.com/files/119727/ICS-SCADA-PLC-Google-Shodanhq-Cheat-Sheet.html