Safety chain device and safety protection system for escalator

A safety protection system for an escalator, characterized in that, comprising:

• a safety chain device comprising:
• a safety chain including a plurality of protective switches coupled in series, each protective switch is configured to switch from a first state to a second state in the event of abnormal operation of a respective corresponding drive chain;
• a resistive network encoder having a plurality of encoder output values, each of the encoder output values corresponds to one of combinations of states of the plurality of protective switches;
• a processor coupled with the resistive network encoder and configured to output a level signal corresponding to one of the encoder output values;
• a first controlled current source coupled with the safety chain and configured to output a first current corresponding to a current flowing through the safety chain;
• and
• a second controlled current source coupled with the processor and configured to output a second current corresponding to the level signal;
• a control unit coupled with the first controlled current source and the second controlled current source and configured to perform corresponding safety protection operations in response to the first current and the second current.