Remote terminal apparatus for programmable controller

A programmable controller remote terminal apparatus connectable to a programmable controller through a fieldbus, said programmable controller being adapted to capture IN data from an input device through the fieldbus, perform logic operation for the captured IN data with a user program, and transmit OUT data as a result of the operation to an output device though the fieldbus, the apparatus comprising:

• a communication unit which is configured to communicate IN data or OUT data with the programmable controller through the fieldbus;
• and
• a plurality of Input/Output (I/O) units to each of which at least either one of the input device or the output device is connected and each of which is configured to communicate with the communication unit through a serial bus line, the communication unit comprising:
• a device which obtains unit information for identifying a model type for each I/O unit connected through the serial bus line and setting value information set for operating said each I/O unit,
• a backup device configured to store the unit information and setting value information of each I/O unit in a storage medium included in the communication unit, and
• a restoration device for transferring the setting value information stored by the backup device to a newly joined I/O unit,
• wherein the communication unit is configured to recognize the presence of an I/O unit comprising information different from the backup information among the connected I/O units through the serial bus line by comparing unit information and setting value information of each I/O unit obtained by the obtaining device to the unit information and the setting value information stored in the storage medium of the backup device.