Memory Organization
Chapter 7
7-7
You can adjust the size of a data table at any time during programming or
editing. Using the 1770-T3 terminal, you can expand the data table in
steps of two words from 48 words to 256 words and then in steps of 128
words to 1,920 words for a Mini-PLC-2/02, 3,968 words for a
Mini-PLC-2/16 or 7,808 words for a Mini-PLC-2/17.
You can expand the data table to accommodate the full I/O capacity of the
processor. Expanding the data table provides more timer/counters or up to
488 timers/counters maximum and space for files (see chapter 11).
Expanding the data table reduces the size of the user program and memory
storage area. You should allow sufficient room for both data table and
user program.
To use the data table to its fullest capacity, remember the following:
The processor initially reserves the first 128 words in the memory for
the data table.
You can adjust the data table size in two word increments to 256 words.
Then, you can increase the data table size in blocks of 128 words.
When the data table is set to 256 words, you can program up to 104
timer/counter instructions.
If a block transfer instruction in your program addresses a module in
rack 2 and you have a 1770-T3 series A or B terminal, you cannot
decrease the size of the data table but you can increase it. You can use
the two GET method for performing block transfers in rack 2 (see
chapter 18).
To expand your data table to any size between 48 and 128 words, do this:
SEARCH The word SEARCH appears in the lower left hand corner of the screen.
50
DATA TABLE CONFIGURATION
NUMBER OF 128-WORD D. T. BLOCKS 01
NUMBER OF INPUT/OUTPUT RACKS 2
NUMBER OF T/C (if available) 040
DATA TABLE SIZE 0128
This illustration shows a factory-configured data table. The numbers
shown are default values. Numbers must be replaced by user-entered
values.
Enter the number of timer/counters equivalent to the size of the data table
(Table 7.A).
Adjusting the Data Table
Expanding the Data Table
Between 48 and 128 Words
