GE EPM 9650/9800 manual Downloading Logs Overview, Byte Range

Chapter 5

Logs, Port Control and Updating Programmable Settings

5.1: Downloading Logs - Overview

A Modbus Master uses a Log Window consisting of 64 Registers to retrieve logs from an EPM Slave. A log is divided into numbered sections called Indexes, which are transferred through the Log Window in sequence. Each of the EPM Monitor’s four ports act independently, allowing multiple Modbus Masters access to all the retrievable data in an EPM Slave.

Downloading any log involves the following types of Registers:

Log Snapshot Header: Header blocks for the different logs begin at Register 36865: This block of Registers holds the following information about the log:

—Memory Size: 4-byte unsigned integers representing the amount of memory, in bytes, allocated to the log.

—Record Size: an unsigned integer representing the size, in bytes, of a record in the log.

—First Index: an unsigned integer representing the index of the first (oldest) record in the log.

—Last Index: an unsigned integer representing the index of the last (newest) record in the log. The value FFFFH indicates that the log is empty.

—First Time Stamp: These Registers hold the time stamp from the first (oldest) record in

Byte	Range		Description
0	0	– 255	century
1	0	– 99	year
2	1	– 12	month
3	1	– 31	day
4	0	– 23	hour
5	0	– 59	minute
6	0	– 59	second
7	0	– 99	centisecond

—Last Time Stamp: These Registers hold the time stamp from the last (newest) record in the Log. The byte order and description are the same for the first time stamp.

—Valid Bitmap: These Registers hold the bit flags indicating whether the EPM Slave recognizes the lines in the Historical Log Settings block (the block beginning at Register 45204). The first bit represents the validity of the last Data Pointer in the Historical Log Settings. A value of 1 means the Data Pointer is acceptable and can be stored. A value of 0 means that the Data Pointer is invalid or unrecognized and can not be stored.

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