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Siemens AG
Entry type: FAQ, Entry ID: 16503831, Entry date: 07/30/2003

Memory reset request by the CPU

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Why does my S7-300 CPU stop with a request for a memory reset after having transferred a project onto my MMC? 

When a project containing an invalid block or an invalid operand for the CPU, is transfered onto the MMC, the CPU stops with a request for a memory reset.
In this situation, there is no possibility to get access to the CPU via Step 7 or to run a diagnostics. The reason for that is that the MMC (Micro Memory Card) is not deleted by the memory reset, and therefore a new memory reset is requested.

Switch the CPU to STOP. Pull the MMC out of the CPU and confirm the request for a memory reset. The memory reset of the CPU after the pull-out of the Micro Memory Card, recovers defined ratios. The CPU is now accessable communicationwise and the diagnostics buffer can be analysed .