Hi aamirawan91,

aamirawan91

1. If I replace an S7-300 CPU, which operates with an MMC, with another CPU having the exact same article number, do I need to download the program again using PG? Alternatively, will just inserting the MMC from the previously installed CPU make it work, considering the MMC contains all the necessary data and program?

You can insert the MMC into the same type of PLC as well as into a compatible successor, and the program will start working as it did after transferring the program to the MMC (loading it into the PLC). However, since the PLC does not write data back to the MMC during operation, the program will work with its default values.

aamirawan91

2. Do S7-1500 CPUs always require a memory card for operation, similar to the S7-300s? Additionally, is the process of replacing 1500 CPUs the same as in the first question?

Yes, a SIMATIC memory card is required to operate a S7-1500 CPU (please refer to function manual 'Structure and Use of the CPU Memory'). The behaviour when replacing the CPU is similar to the S7-300.

aamirawan91

3. Do S7-1200 CPUs operate without the need for a memory card, given their large built-in memory capacity?

Compared to the S7-1200, the internal memory of the S7-1500 is much larger. However, the S7-1200 is designed so that a small amount of internal memory can be used as load memory. If this is not enough, a SIMATIC memory card must be used instead.

aamirawan91

4. Where are recipes exactly saved? I believed we had options to save them either in the HMI flash memory or on the HMI SD card/memory card. However, the other day, when we replaced a 1500 CPU with a new one and used the MMC from the previously installed dead CPU, it worked, but the recipes were all reset.

In the case of an S7-1500, you can export recipe data as a CSV file to the SIMATIC memory card. This allows import after the CPU has been replaced. See 'Memory usage for recipes' for more details.

Kind regards
Stefan