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S7-400 CPU 41x -- Product information -- Background and system information

	What are the differences between OPEN MODBUS / TCP Redundant V1 and OPEN MODBUS / TCP Redundant V2?
	What is the difference between "normal routing" and data record routing?
	Which SIMATIC S7-300/S7-400 modules support the NTP time-of-day message and how do you activate this kind of time synchronization?
	Which manufacturer ID, in other words OUI (Organizationally Unique Identifier), does SIEMENS AG use for the MAC addresses of network-compatible devices?
	What should you watch out for when adding components or changing their parameters using CiR (Configuration in Run)?
	Which IO controllers and IO devices support the following functions: IRT, prioritized startup, MRP, PROFIenergy, Shared device, I device and clock-synchronized mode?
	Which types of connection/protocols do the S7-300/400 CPUs and the CPs support by default?
	Which PROFINET nodes support automatic commissioning and the replace device without interchangeable medium function?
	Behavior of the CPU after power off without back-up battery
	I/O addressing with DP slaves
	Which PROFINET nodes support the extended PN diagnostics and what do you have to configure?
	What is the difference between a restart (warm restart), cold restart and hot restart of a S7-400 CPU?
	Which SIMATIC S7 modules support the "Direct Data Exchange" function (internode communication)?
	What properties, advantages and special features does the S7 Basis Communication offer?
	What properties, advantages and special features does the global data communication offer?
	Which entries deal with consistent data in conjunction with distributed I/O?
	What is the connection between subnet masks and IP addresses with regard to subnetting and supernetting (Classless Inter Domain Routing CIDR)?
	What are the requirements for using the S7 routing function and which modules can you implement?
	CPU does not work in RUN
	What does "Correction factor" mean in the "Diagnostics/Clock" tab of the CPU's Properties dialog?
	What is multicomputing mode and what are the differences to operating in the segmented subrack?
	Differing information on the requirement of offline/ online memory
	How can I get an overview of the S7-400 memory concept?

Behavior of the CPU after power off without back-up battery

Part number:

QUESTION:
Is the status of an S7-400 CPU after power off/on (without back-up battery) the same as the state after an overall reset?

ANSWER:
In the case of power failure or an overall reset (MRES) in non-back-up mode the following memory areas of the S7-400-CPU are reset:

Dynamic load memory (RAM)
Main memory
System memory

All the data that is stored in these areas is lost with the exception of the MPI parameters (e.g. MPI address of the CPU). These remain after a power failure. Thus, in both cases the CPU behaves identically, which means that after a power failure or an overall reset, the CPU still remains able to communicate. After power failure, the only way of starting is a Restart.

Important:
In non-back-up mode there are no remanent memory areas.

Entry ID:1994237

Date:2000-03-14

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