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S7-300 CPU 31x -- Product information -- Background and system information

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	Retentivity behavior of S7-300 CPU 31x and complete devices C7-6xx with MMC
	Status of the run-time meter after overall reset
	Why does the retentivity behavior of the S7-300 CPUs and C7 devices without MMC (Micro Memory Card) influence the contents of the variables?
	Local data addressing with S7-300 / S7 400
	S7 300 run-time meter doesn't give any value

Status of the run-time meter after overall reset

Part number:

QUESTION:
Is the run-time meter reset after an overall reset of the CPU?

ANSWER:
In the S7-300 and C7 complete devices a difference is made between CPUs with a hardware clock (integrated "real-time clock") and CPUs with a software clock. The last run-time meter value in the CPUs with a software clock with no back-up is deleted after an overall reset of the CPU. In the case of the CPUs with a hardware clock with back-up, the last run-time meter value is retained after an overall reset of the CPU.

Table 1 lists the CPUs with software clock. All other S7-300 CPUs and C7 complete devices have a hardware clock. The S7-400 CPUs all have hardware clocks.

CPU

Order no.

Run-time meter value is deleted/retained

CPU 312-IFM

6ES7 312-5AC0x-0AB0

No run-time meter

CPU 313

6ES7 313-1AD0x-0AB0

Deleted

CPU312

6ES7 312-1AD10-0AB0

Deleted

CPU312C

6ES7 312-5BD0x-0AB0

Deleted

C7-621

6ES7 621-1AD0x-0AE3

Deleted

C7-621 ASi

6ES7 621-6BD0x-0AE3

Deleted

Table 1: S7-300 CPUs and C7 complete devices with software clock

Entry ID:2804630

Date:2003-11-05

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