| 摘要 |
This is a process in which a first computer (6) is linked to the safety facility (4) and in which a second computer (12) intended to control an actuator (2) interrogates prior to any command to turn on and/or turn off the actuator (2) the first computer (6) as to the state of the safety facility (4). The second computer (12) interrogates the state of the safety facility (4) directly by sending an encrypted message. The first computer (6) forwards in one direction the question of the second computer (12) to the safety facility (4) and in the opposite direction the response of the latter. The second computer (12) verifies the consistency of the response received. The encryption code is known to the second computer (12) and to the safety facility (4) but is unknown to the first computer (6).
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