Applications 7 And 8: 1Oo2 Evaluation Of 3-Wire, Non-Equivalent Sensor Circuit - Siemens SIMATIC S7 Functional Safety Manual

Fail-Safe signal module (SM) applications
3.1 Digital input applications
3.1.5

Applications 7 and 8: 1oo2 evaluation of 3-wire, non-equivalent sensor circuit

In non-equivalent mode, short-circuit testing can be enabled on a 3-wire circuit. The module
expects that the logic "0" circuit will not change with the sensor dark test.
Figure 3-7 F-DI Application mode 7: Internal sensor supply
Figure 3-8 F-DI Application mode 8: External sensor supply
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S7-1200 Functional Safety Manual
Manual, 02/2015, A5E03470344-AA