GE GFK-0787B user manual Register %R Memory Assignment for GMR

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Register (%R) Memory Assignment for GMR

The GMR software uses several areas of %R memory for specific functions, as diagrammed below. Only the area labelled ªApplication Registersº should be used by the application program. Within that area, a portion is reserved for initialization data, as explained below.

%R Memory Allocation for GMR

%R and %M

Application Registers

Bus Controller. 1 Interface

.

.

Bus Controller N±1 Interface

Bus Controller N Interface

Global Data to be Sent

Global Data Received from PLC on Bus a with highest serial bus address

Global Data Received from PLC on Bus a with lower serial bus address

Global Data Received from PLC on Bus b with highest serial bus address

Global Data Received from PLC on Bus b with lower serial bus address

%R1

%Rmax±451

%Rmax±385

%Rmax±319

%Rmax±255

%Rmax±191

%Rmax±127

%Rmax±63

Initialization Data

Defaults

66 words

66words

66words

64words

64words

64words

64words

64words

%Rmax±320+66xN

%Rmax±452

%Rmax±386

%Rmax±320

%Rmax±256

%Rmax±192

%Rmax±128

%Rmax±64

%Rmax

Each PLC receives two sets of incoming Global Data from the other PLC(s). Both of these are placed into %R memory, as can be seen in the diagram. Only one set is copied to %G memory for access by the application program, however.

Directly ahead of the incoming Global Data in %R memory is a copy of the outgoing

Global Data. This data should be programmed using %G memory, not %R memory. The

GMR software automatically moves the data to the appropriate %R location prior to the

Global Data being sent.

Ahead of the Global Data areas of %R memory are additional areas used by the GMR software for communications with I/O blocks (for functions such as autotesting and diagnostics) and with other bus controllers on the bus. The overall length of this area depends on the number of other bus controllers in the system.

%R Memory Required for Startup Initialization Data

%R and %M initialization data that may be received during startup are stored in %R memory (the second set of incoming %M initialization data is stored there temporarily at startup).

The GMR Configuration Software default for the beginning of the initialization data is %R0001.

In addition, by default, the configuration software assigns %R0257 as the beginning location for %M initialization data which is directly after the %R initialization data.

GFK-0787B Chapter 7 Programming Information 7-9