Annex B : Additional information (informative)

B.2 Use cases for Operator Acknowledgment

B.2.5 Use case 4: bidirectional comm. and single, two-sided OA

Figure 34 – One sided OA on each side is possible

Figure 34 shows a scenario where an operator acknowledgment activated at controller A or controller B suffices for re-establishing the bidirectional connection. Both sides will cease delivering fail-safe values and continue sending process values. This is accomplished by the logic circuits shown in the safety applications.