Memory Map Information; User-Definable Memory Map Area; Event Recorder - GE 469 Instruction Manual

6.3 MEMORY MAP
6.3MEMORY MAP
The data stored in the 469 is grouped as Setpoints and Actual Values. Setpoints can be read and written by a master com-
puter. Actual Values are read only. All Setpoints and Actual Values are stored as two-byte values. That is, each register
address is the address of a two-byte value. Addresses are listed in hexadecimal. Data values (setpoint ranges, increments,
factory values) are in decimal.
Many Modbus communications drivers add 40001d to the actual address of the register addresses. For example: if
address 0h was to be read, 40001d would be the address required by the Modbus communications driver; if
NOTE
address 320h (800d) was to be read, 40801d would be the address required by the Modbus communications driver.
The 469 has a powerful feature, called the User Definable Memory Map, which allows a computer to read up to 124 non-
consecutive data registers (setpoints or actual values) by using one Modbus packet. It is often necessary for a master com-
puter to continuously poll various values in each of the connected slave relays. If these values are scattered throughout the
memory map, reading them would require numerous transmissions and would burden the communication link. The User
Definable Memory Map can be programmed to join any memory map address to one in the block of consecutive User Map
locations, so that they can be accessed by reading these consecutive locations.
The User Definable area has two sections:
1. A register index area (memory map addresses 0180h to 01FCh) that contains 125 actual values or setpoints register
addresses.
2. A register area (memory map addresses 0100h to 017Ch) that contains the data at the addresses in the register index.
Register data that is separated in the rest of the memory map may be remapped to adjacent register addresses in the User
Definable Registers area. This is accomplished by writing to register addresses in the User Definable Register Index area.
This allows for improved through-put of data and can eliminate the need for multiple read command sequences.
For example, if the values of Average Phase Current (register address 0306h) and Hottest Stator RTD Temperature (regis-
ter address 0320h) are required to be read from an 469, their addresses may be remapped as follows:
1. Write 0306h to address 0180h (User Definable Register Index 0000) using function code 06 or 16.
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2. Write 0307h to address 0181h (User Definable Register Index 0001) using function code 06 or 16.
(Average Phase Current is a double register number)
3. Write 0320h to address 0182h (User Definable Register Index 0001) using function code 06 or 16.
A read (function code 03 or 04) of registers 0100h (User Definable Register 0000) and 0101h (User Definable Register
0001) will return the Phase A Current and register 0102h (User Definable Register 0002) will return Hottest Stator RTD
Temperature.
The 469 event recorder data starts at address 3000h. Address 3003h is a pointer to the event of interest (1 representing the
latest event and 40 representing the oldest event). To retrieve Event 1, write '1' to the Event Record Selector (3003h) and
read the data from 3004h to 3022h. To retrieve Event 2, write '2' to the Event Record Selector (3003h) and read the data
from 3004h to 3022h. All 40 events may be retrieved in this manner. The time and date stamp of each event may be used
to ensure that all events have been retrieved in order without new events corrupting the sequence of events (Event 1
should be more recent than Event 2, Event 2 should be more recent than Event 3, etc.).
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Courtesy of NationalSwitchgear.com

6.3.2 USER-DEFINABLE MEMORY MAP AREA

469 Motor Management Relay
6 COMMUNICATIONS

6.3.1 MEMORY MAP INFORMATION

6.3.3 EVENT RECORDER

GE Multilin