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Mark V Accumulator
Configuration and function of accumulator in MarkV

We have MarkV at site, I am trying to understand the configuration & function of Accumulator. ACCUM.DEF file defines the use of different accumulators. But I want to understand where this accumulator fetches value.

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I have never seen ACCUM.DEF, but I would like to.

I’m not exactly sure what you’re asking (though I have a suspicion as to why you’re asking), but accumulator values are stored in EEPROM, a non-volatile memory area (meaning that the values stored in this kind of memory are retained (are not lost) when power to the memory is cycled.

The accumulator values are written to the EEPROM memory locations from RAM (which is a volatile area of memory) approximately once per hour, by the operating system of the Mark V control processors. The Mark V operator interface can access and display the RAM values in engineering units (whole numbers; time; etc.). The RAM values get “restored” (initialized) during booting of the processors from the values stored in EEPROM.

The values stored in EEPROM can also be written to by downloading by the EEPROM Downloader of a Mark V operator interface from the file TOTD_Q.DAT (for Mark V <I> Operator interfaces) or TOTD_Q.AP1 (for GE Mark V HMI interfaces). The EEPROM Downloader can also be used to upload the EEPROM accumulator values to the aforementioned files.

The aforementioned files are specially created files that store the accumulator values in a GE proprietary format, because unscrupulous people might change the values for nefarious purposes in order to obtain warranty services and/or parts they were not entitled to. There are rumours that some individuals have “broken the code” but there are also anecdotal stories of strange issues after their files have been downloaded to a Mark V. GE has modified the aforementioned files for many sites to correct values for various reasons.

It’s a tricky business downloading the aforementioned files to EEPROM and should only be done by knowledgeable people who know what they are downloading and how to re-boot the processors, because downloading old data to a running Mark V can cause some very strange problems (which include values that appear to mysteriously change over time, rising and falling periodically).

Hope this helps! If you could post ACCUM.DEF to a file sharing location on the World Wide Web and then post a link to that site in a response to this thread that would be much appreciated.

By CuriousOne on 28 April, 2019 - 10:41 pm

Well written reply CSA!