The standard EEPROM on M-series support either 1770 x16-bit integer OR approximately 87 strings of 40 bytes each.
With M2018P optional EEPROM you can expand the program memory to 8190 words, and data EEPROM to 7750 16-bit integer OR approx 387 strings.
Your requirement for storing 1428 strings of 12 byte each is not possible on the M-series PLC as it exceeds the maximum amount of available EEPROM memory for storing either integer or strings.
However, since the PLC is able to send data out of its RS232 port you may be able to find a third party RS232 EEPROM storage solution to store more data.