Siemens SIMATIC S7 Functional Safety Manual page 205

Safety mode
1. Safety mode is the operating mode of the fail-safe signal modules (SM) that allows
safety-related communication using safety message frames. S7-1200 fail-safe SMs are
designed for safety mode only.
2. Operating mode of the safety program: In safety mode of the safety program, all safety
mechanisms for fault detection and fault reaction are activated. The safety program
cannot be modified during operation in safety mode. Safety mode can be deactivated by
the user (deactivated safety mode).
Safety program
The safety program is a safety-related user program.
Sensor
Field device that converts a physical quantity (for example, location, temperature, or speed)
into an electrical signal that can be read by the PLC. The only fail-safe sensor inputs
presently available for the S7-1200 are digital (binary) ON/OFF inputs operating at 24 VDC
nominal.
SIL
Safety Integrity Level (SIL) values 1 through 4 are defined in IEC 61508. A higher safety
integrity level is associated with a lower probability of dangerous failure.
Standard user program
The standard user program is a non-safety-related user program.
S7-1200 Functional Safety Manual
Manual, 02/2015, A5E03470344-AA
Glossary
205