SOLEIL is a third generation Synchrotron radiation source located in France near Paris, having the classical accelerator structure consisting of a Linac pre-accelerator, a Booster accelerator and a Storage Ring, which are connected by two transfer lines. Since 2006, the Storage Ring delivers photon beam to beamlines. In order to protect the very sensitive and essential equipment during machine operation, (vacuum chambers, vacuum valves, mirrors, etc.) an interlock system has been implemented. This system is based on industrial and autonomous PLC (Programmable Logic Controller). Interlock system and subsystems are based on Siemens PLCs S7-300 family products, which are standard hardware components of SOLEIL Control Systems. Surrounding the booster and the 354 meters of the storage ring, 87 PLCs configurations are installed with 50 for vacuum security, 19 for diagnostics subsystem security and 18 for the interlock system. PLC cycle time ensures a signal between detection and RF interlock generation around 30 and 50 ms.