Rockwell Automation 2755-DM9, -DM9E High Speed Decoder - Manual (Page 25)

Chapter 3
How the Decoder Operates
3–6
Before you try to change the operating configuration of the decoder, you
should understand how configuration parameters are stored. The decoder has
two types of memory:
•
EEPROM- Electrically Erasable Programmable Read Only Memory
contains the “non-volatile” operating configuration of the decoder. The
term “non-volatile” means that the memory is not lost when you turn the
power off or restart the decoder.
•
RAM- Random Access Memory contains the current operating
configuration of the decoder. Any changes made to the the operating
configuration of the decoder are made to the decoder’s RAM. All
information stored in the RAM is erased when the power to the decoder is
turned off. When the decoder is turned back on (rebooted), the
configuration parameters are copied from non-volatile memory
(EEPROM) to the RAM.
Figure 3.6 illustrates the relationship between the RAM and EEPROM
memory. Notice that the user interface is with the RAM memory. Also,
notice that the decoder transfers the contents of the RAM to the EEPROM
during a SAVE operation and copies the same contents from the EEPROM to
RAM during startup.
Note: The configuration in RAM determines the decoder performance
(operating characteristics).
DEFAULT
RECALL
START-UP
RESTART
SAVE
RAM
User Interface
- Programmer
-Host
Default
Configuration
Settings
EEPROM
Figure 3.6
Decoder Memory
Decoder
Performance
When you change the operating configuration of the decoder, you are
changing the configuration stored in the decoder’s RAM. Since the decoder
takes its current operating instructions from RAM, any changes you make
RAM and EEPROM Memory