Memory is where temporary data storage and a place to store the program to be started, where the program is the result of translation of the ladder diagram created by the user. Memory system on the PLC led to flash memory technology. By using flash memory it will be very easy for users to do programming or reprogramming repeatedly. In addition to the flash memory also has EEPROM which can be removed repeatedly.
Memory system is divided into blocks where each block has its own function. Some parts of the memory used to store the status of input and output, while the other parts of the memory used to store variables that are used in programs such as the timer and counter values.
Flash memory is a non-volatile computer storage that can be electrically erased and reprogrammed. It is a technology that is primarily used in memory cards and USB flash drives for general storage and transfer of data between computers and other digital products. It is a specific type of EEPROM (Electrically Erasable Programmable Read-Only Memory) that is erased and programmed in large blocks; in early flash the entire chip had to be erased at once.
Since flash memory is non-volatile, no power is needed to maintain the information stored in the chip. In addition, flash memory offers fast read access times (although not as fast as volatile DRAM memory used for main memory in PCs) and better kinetic shock resistance than hard disks. These characteristics explain the popularity of flash memory in portable devices.