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Siemens AG
Entry type: FAQ Entry ID: 186828, Entry date: 01/12/1998

Configuration data of the DP master interface is lost

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I have transferred the configuration data of the DP interface onto the PLC and the DP bus is running perfectly. If, however, I de-energize the AG 95 in the case of no back-up battery, when I switch on the controller the DP configuration data is no longer on the EEPROM. What could be the cause of this?

In the case of AG 95-DP Master with the version <= 2 this behavior is due to the system. As of release 3 you can set the behavior (validity of DP parameterization after power failure) via a parameter in data block 1. If you want to store the parameterization data of the DP interface on the EEPROM in a de-energized state, then you must change the default setting of the "LNPG” parameter in DP 1 and copy the change data block onto the EEPROM too.

Proceed as follows to make the change:
Parameter block: DPM: LNPG n ; not zero voltage proof
Parameter block: DPM: LNPG y ; zero voltage proof
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A change in DB 1 is only active after doing a cold restart of the PLC.

The exact description of this setting is to be found in the Distributed I/O System ET 200 manual, Edition 03, Page 11-4.

Upgrading version 1 and 2 PLCs is possible at a charge. Please get in touch with your Siemens contact.

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