Siemens SIMATIC S7 Functional Safety Manual page 8

Table of contents
3 Fail-Safe signal module (SM) applications ............................................................................................... 65
3.1 Digital input applications ........................................................................................................ 67
3.1.1 Selecting the digital input application ..................................................................................... 68
3.1.2 Applications 1 and 2: 1oo1 evaluation of a single sensor ...................................................... 69
3.1.3 Applications 3 and 4: 1oo2 evaluation of a single sensor ...................................................... 70
3.1.4 Applications 5 and 6: 1oo2 evaluation of independent equivalent sensors ........................... 71
3.1.5 Applications 7 and 8: 1oo2 evaluation of 3-wire, non-equivalent sensor circuit .................... 72
3.1.6 Applications 9 and 10: 1oo2 evaluation of 4-wire non-equivalent sensor circuit ................... 73
3.2 Digital output applications ...................................................................................................... 74
3.2.1 Selecting the digital output application .................................................................................. 75
3.2.2 Application 1: Wiring a directly-connected SIL-rated actuator ............................................... 75
3.2.3 Application 2: Wiring external contactors: Separate P and M controlled contactors ............. 76
3.2.4 Application 3: Wiring external contactors: Parallel connected between P and M .................. 76
3.2.5 Application 4: Wiring external contactors: Separate P and M output channels for each
contactor ................................................................................................................................ 77
3.2.6 Application 5: Separate circuits of a relay channel controlling external contactors ............... 77
3.2.7 Application 6: Wiring a directly-connected SIL-rated actuator ............................................... 78
3.2.8 Application 7: Wiring a directly-connected SIL-rated actuator, switching both load
conductors .............................................................................................................................. 78
4 Fail-Safe CPU and signal module (SM) installation ................................................................................. 79
4.1 S7-1200 Fail-Safe modules installation and removal ............................................................ 79
4.1.1 Mounting dimensions for S7-1200 Fail-Safe modules ........................................................... 79
4.1.2 Guidelines for installing S7-1200 Fail-Safe devices .............................................................. 80
4.1.3 Installation and removal safety rules ..................................................................................... 83
4.1.4 Installing and removing an S7-1200 FC CPU ........................................................................ 85
4.1.5 Installing and removing a signal module (SM) ....................................................................... 87
4.1.6 Removing and reinstalling the S7-1200 terminal block connector ......................................... 89
4.2 Fail-Safe system electrical design rules ................................................................................ 90
4.2.1 Safe functional extra low voltage requirement (power supplies and other system
components) .......................................................................................................................... 90
4.2.2 Power budget ......................................................................................................................... 91
4.2.2.1 Connecting power to the S7-1200 system ............................................................................. 91
4.2.2.2 Calculating a sample power requirement .............................................................................. 94
4.2.2.3 Calculating your power requirement ...................................................................................... 96
4.2.3 Fail-Safe module electrical characteristics and terminal assignments .................................. 97
4.3 Control system wiring guidelines ........................................................................................... 98
4.3.1 Guidelines for grounding and wiring ...................................................................................... 98
4.3.2 Grounding an S7-1200 system .............................................................................................. 99
4.3.3 Wiring an S7-1200 system ................................................................................................... 100
4.3.4 Guidelines for lamp loads .................................................................................................... 101
4.3.5 Guidelines for inductive loads .............................................................................................. 101
4.4 Maintenance guidelines ....................................................................................................... 104
5 Fail-Safe signal module (SM) I/O configuration ...................................................................................... 105
5.1 Configuring fail-safe SM I/O properties ................................................................................ 105
5.2 Configuring common F-parameters ..................................................................................... 106
5.3 Configuring SM 1226 F-DI 16 x 24 VDC DI and channel parameters ................................. 107
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S7-1200 Functional Safety Manual
Manual, 02/2015, A5E03470344-AA