Write Memory

[PLY]

HI ! I want to write memory in arear at not clear if power OFF.Then ON power the old data not clear.

[support]

Do you mean you want to write to the non-volatile memory? You can use the SAVE_EEP command to save the data to EEPROM memory. These will not be lost after power off. When power on, read the data back using the LOAD_EEP command. There are 1700 words (16-bit) available in the M-series PLC which can be used to store non-volatile data. Note that reading and writing to EEPROM are slow and there is a fixed life cycle (about 100,000 erase/write cycles) so you should exercise necessary caution when using the EEPROM memory.

[whenry]

What constitutes a write cycle.  

1.   If I save 8 pieces of data to 8 memory locations locations using one custom function, does that constitute 8 write cycles.  

2.  Everytime A new or updated program is loaded into the PLC is that just one write cycle, or are the number of program words counted?

[support]

Write cycles is per memory location. So if you write 8 data to 8 different locations, each location only undergoes 1 write cycle.

When you transfer program to the PLC, each complete transfer is considered 1 cycle.

Anyway, the program EEPROM and data EEPROM occupies different memory locations so they are independent of each other.