Traffic signal system safety circuit - has two processors receiving signal state combinations for checking their reliability

摘要

Signal condition sensors are fitted in the conducting lines carrying the control signal combinations (AK). The sensors pass the signal conditions periodically to a monitoring processor (BP). The processor (BP) undertakes a procedure testing the reliability of the signal combinations and in case of any unreliability being established gives a safety warning signal (SM1) to a safety relay. The relay passes the signal combination to an output processor (AP) which compares it with a control combination (ZK) that is, the combination required, and another warning (SM2) is given if these are different. ADVANTAGE - Improvement in reliability.