Management system for control program of industrial controller

A management system for a control program of an industrial controller, the management system comprising:

• a first server apparatus including a first processor and a first database in which the control program is registered;
• and
• a second server apparatus including a second processor and a second database in which the control program is registered;
• and
• a single or a plurality of client apparatuses including a third processor, wherein:
• during ordinary operation, the first processor of the first server apparatus is in a master state, the second processor of the second server apparatus is in a backup state, and the second server apparatus belongs to a first group that receives data sent from the first server apparatus;
• during the ordinary operation, the client apparatus belongs to the first group;
• the first processor of the first server apparatus sends a first health signal to an address of the first group by multicast communication with a constant period;
• and
• the second processor of the second server apparatus switches from the backup state to the master state, based on the first health signal sent from the first server apparatus to the address of the first group;
• when the second processor of the second server apparatus switches to the master state, the second processor of the second server apparatus breaks away from the first group, and generates a second group that receives data sent from the second server apparatus;
• and
• the third processor of the client apparatus breaks away from the first group and belongs to the second group, based on the first health signal sent from the first server apparatus to the address of the first group, wherein:
• the first processor of the first server apparatus creates a first update history when updating the first database, and the second processor of the second server apparatus performs equalization from the first database to the second database, based on the first update history;
• and
• the second processor of the second server apparatus creates a second update history when updating the second database, and the first processor of the first server apparatus performs equalization from the second database to the first database, based on the second update history.