Data Start Pointer Offset (Word 10): This word contains the offset within the memory type
selected in the Data Memory Type word (Word 9). Note: The Data Start Pointer Offset is a
zero-based number. In practical terms, this means that you should subtract one from the
address number that you wish to specify. For example, to select %R0001 as the Data Start
location, enter zero (1 – 1 = 0). Or, to select %R0100, enter 99 (100 – 1 = 99). Note that the
memory type, %R in this example, is specified in the previous word. The starting address
designated by this word will be the first of 1024 contiguous words of memory used in the
COMM REQ.
B-3.3 User Data Table COMM REQ Example
In this example, the following specifications are given:
•
The DSM314 module is mounted in Rack 0, Slot 7 of the PLC.
•
The Command Block’s starting address is %R0196.
•
The Status Word is located at %R0195.
•
The COMM REQ’s FT (fault) output drives a Set Coil.
•
Segment 1 of the DSM314 User Data Table is to be Written to. This is specified by
the Command Code D001 in Word 7 of the Command Block.
•
The data in a 1024-word (2048 byte) portion of register memory, %R0301 through
%R1324, is copied and written into Segment 1 (2048 bytes) of the User Data Table.
(Note that each %R word is two bytes in length.) This transfer of data is illustrated in
the next figure:
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