NVRAM

KAS uses NVRAM to save Retain Variables.

Hardware Type	NVRAM Size Allocation
KAS Simulator	256 Kbytes
PCMM2G	256 Kbytes

• 
  

• Part of NVRAM allocation is reserved to store some internal data (144 bytes).
  As a consequence, not all of the complete physical NVRAM is available for the retain variables.

If the size is big enough, KAS updates the non-volatile memory to store the retain variables values.

• This operation is performed in the background every 20 seconds.
• The frequency increases to every two seconds when the application is running or when you shutdown the application.

NVRAM Life Expectancy

• Data Retention: At maximum operating temperature, the data written to the memory is retained for 10 years.
• Endurance: NVRAM memory has an endurance limit of 10¹⁴ read / write accesses.
  • More than 6,000,000 years of being accessed every 2 seconds.

• 
  
• • Using the retain variables is very cycle time consuming.
  • As a consequence, Kollmorgen strongly recommends to carefully monitor the system load with the TraceTimes command.
  • See Oscilloscope Control Panel.

Verify the NVRAM Space

To calculate NVRAM space, add the size of each retained variable according to the:

• Data Types
• Arrays - The numbers of elements in case the variable is declared as an array.

Remember! Add the 144 bytes!

In Figure 1, the total size is: 3684 bits (which is less than 0.5 Kbytes).

Figure 1: Example: Retain variables

Variable	Size / element	Number of Element	Total Size / variable
bLedStatus	1-bit	4	4
Internal data	1152-bits (144 bytes)	N/A	1152
MasterAbsPos	64-bits	1	64
MyString	800-bits (100 bytes)	3	2400
TravelSpeed	64-bits	1	64