How do you calculate the service life of a memory card of the S7-1500/S7-1200 and ET 200?
The "Technical Data" and the following table give the following specifications for the SIMATIC S7 Memory Cards (SMC):
|Number of delete/write procedures|
|Min. data retention|
(after last programming)
|6ES7954-8LB01-0AA0||SIMATIC Memory Card, 2 MB|
|6ES7954-8LC01-0AA0||SIMATIC Memory Card, 4 MB||500,000|
|6ES7954-8LC02-0AA0||SIMATIC Memory Card, 4 MB||500,000||10 years1)|
|6ES7954-8LE01-0AA0||SIMATIC Memory Card, 12 MB||500,000||10 years1)|
|6ES7954-8LE02-0AA0||SIMATIC Memory Card, 12 MB||500,000||10 years1)|
|6ES7954-8LF01-0AA0||SIMATIC Memory Card, 24 MB||500,000||10 years1)|
|6ES7954-8LF02-0AA0||SIMATIC Memory Card, 24 MB||500,000||10 years1)|
|6ES7954-8LL02-0AA0||SIMATIC Memory Card, 256 MB||200,000||10 years2)|
|6ES7954-8LP01-0AA0||SIMATIC Memory Card, 2 GB||100,000||10 years5)|
|6ES7954-8LP02-0AA0||SIMATIC Memory Card, 2 GB||60,000||10 years3)|
|6ES7954-8LT02-0AA0||SIMATIC Memory Card, 32 GB||50,000||10 years4)|
|6ES7954-8LT03-0AA0||SIMATIC Memory Card, 32 GB||100,000||10 years5)|
1) 10 years if the number of delete/write procedures is <50,000 (1 year if the number of delete/write procedures is > 450,000)
2) 10 years if the number of delete/write procedures is < 20,000 (1 year if the number of delete/write procedures is > 180,000)
3) 10 years if the number of delete/write procedures is < 6,000 (1 year if the number of delete/write procedures is > 54,000)
4) 10 years if the number of delete/write procedures is < 5,000 (1 year if the number of delete/write procedures is > 45,000)
5) 10 years if the number of delete/write procedures is < 10,000 (1 year if the number of delete/write procedures is > 90,000)
The 10% rule of the maximum number of delete/write cycles is valid for all SIMATIC S7 Memory Cards.
For example, for the 32 GB SMC (6ES7 954-8LT03-0AA0) the stored data is retained at least 10 years if the number of delete/write procedures is less than 10,000.
If the number of delete/write procedures is greater than 90,000, data is guaranteed to be retained for 1 year.
Calculation of the service life for the 32 GB SMC (6ES7 954-8LT03-0AA0)
The example below shows which write volume is available for the 32 GB SMC.
- The 32 GB SMC(...-8LT03-0AA0) is specified with 100,000 delete/write procedures.
- You can access each byte (write or delete) 100,000 times.
- The memory size of the SMC is approx. 32,000,000,000 bytes.
- The additionally created internal meta data has an effect of a factor of 100 on the write volume.
You can generally calculate the write volume for SIMATIC S7 Memory Cards as follows:
|Write volume||=||-------------------------------------||*||Minimum number of delete/write procedures|
|Amount of internal meta data|
|The following holds for the 32 GB SMC:|
|Write volume||=||32 TB|
You calculate the service life of the 32 GB SMC as follows:
If you write one data block of 160 bytes to the SMC per second, then the safe data storage on the SMC is 32 TB / 160 bytes/s = 200,000,000,000 seconds
(theoretically 6334 years assuming 1 year = 365.24 days).
If you write one Data Log (csv) of 160 KB to your SMC per second, then the safe data storage on the SMC is 32 TB / 160 KB/s = 200,000,000 seconds (theoretically 6.34 years).
Ignored here are the operations like writing and deleting in MS Windows and the downloading of projects, because these do not occur as often as the above-mentioned operations.
With the S7-1500 CPU modules a message is displayed in the diagnostics buffer when 80% of the minimum service life of the SMC is exceeded. The MAINT LED lights when 100% of the minimum service life is attained. This function is not supported by the following SIMATIC Memory Cards if the firmware version of the S7-1500 CPU module is less than V2.0.
- 2 GB, (article no. 6ES7 954-8LP02-0AA0)
- 32 GB, (article no. 6ES7 954-8LT02-0AA0)
- 32 GB, (article no. 6ES7 954-8LT03-0AA0)
The "GetSMCinfo" block is available with firmware version V2.1 and higher of the S7-1500 CPU module.
This block enables you to display a diagnostics entry when a defined service life duration is exceeded.
The block provides access to the following information in the user program:
Percentage value of the delete and write procedures already performed on the SMC with reference to the number of guaranteed delete and write procedures (50,000; 100,000; etc.).
In the case of intensive usage (recipes and archives, for example) you can evaluate the service life information of your SMC and replace it accordingly at a defined time as part of your maintenance schedule.
The blocks listed in the table below have read/write access to the SMC:
|FB||SET_TIMEZONE||Set time zone|
|SFC 84||WRIT_DBL||Write to the data block in the load memory|
|SFC 84||CREATE_DB||Create a data block|
|SFC 95||DELETE_DB||Delete a data block|
|SFB 140||DataLogCreate||Create a data log|
|SFB 142||DataLogWrite||Write a data log|
|SFB 143||DataLogClear||Clear a data log|
|SFB 144||DataLogClose||Close a data log|
|SFB 145||DataLogDelete||Delete a data log|
|SFB 147||DataLogOpen||Open a data log|
|SFB 148||DataLogNewFile||Data log in a new file|
|SFB 1003||RecipeExport||Export a recipe|
If you call the blocks listed in the table cyclically, this can significantly shorten the service life of the SMC.