NVRAM

KAS uses NVRAM to save Retain Variables.

Hardware Type	NVRAM Size Allocation
Simulator	256 Kbytes
AKD PDMM or PCMM	32 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.

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 this example, the total size is: 3684 bits (which is less than 0.5 Kbytes).

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