Description:
To get the serial number of the MMC, you must read the data out of the system status list (SSL) using SFC 51 "RDSYSST":

• SSL ID W#16#011C "Identification of a component"
• Index W#16#0008 "Serial number of the memory card"

Reading out of this data is possible with all SIMATIC S7-300 CPUs and C7 complete devices with MMC as from firmware V2.0 (CPU 317: as from V2.1).

Notes on output of SFC51:
When you read out the serial number of an MMC with SFC51 on the Field PG, the output data of the SFC51 is different to the serial number of the MMC. The reason for this system-specific behavior is that the digits of the hexadecimal code have been resorted through processing of the SFC51. For the output of a serial number, e.g. 1342498713, with the SFC51 you get the value 99E70450_{Hex .}

The table below explains how the SFC51 output is made after resorting of the digits.
 

Serial number of the MMC:	1342498713
Hex code of the serial number:	5	0	0	4	E	7	9	9
Designation of the digits:	a1	a2	b1	b2	c1	c2	d1	d2
Digits are resorted with SFC51:	d1	d2	c1	c2	b1	b2	a1	a2
Display via SFC51:	9	9	E	7	0	4	5	0

Sample project:
Save the MmcSerNr.zip file in a separate directory and then dearchive it. The S7 project then unpacks with all the associated subdirectories. You can use the SIMATIC Manager to open and process the extracted project

Attachment 01: MmcSerNr.zip  ( 30 KB )

IMPORTANT
The sample program is freeware. Any user can use, copy and forward this program FREE OF CHARGE. The authors and owners of this program take no responsibility whatsoever for the functionality and compatibility of this software. Use of the software is at the user's own risk. Since this software is free of charge, there is no warranty nor entitlement to error correction and hotline support.