Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual - Manual (Page 56)

Data Table
Chapter 3
3Ć29
placement can be found in the PLC-2/20, PLC-2/30 Programmable
Controller Assembly and Installation Manual (publication no. 1772-6.6.2).
In addition to I/O assignments, timers and counters must also be assigned
data table word addresses. It is best to make a list of the word addresses
used for timers and counters on data table documentation forms. Later,
when sizing the data table, this list will be useful.
The first available timer/counter address depends on the number of I/O
racks used. The PLC-2/30 Processor (Cat. No. 1772-LP3) can have up to 7
I/O racks. The corresponding addresses for the first timer/counter locations
are shown in Table 3.B. If block transfer is to be used, each block transfer
instruction requires one T/C address pair as its data address. The first
available location must be reserved for block transfer (Chapter 10).
Table 3.B
Timer/Counter Address for 1772ĆLP3
# I/O Racks First Timer/Counter Word Address
1
2
3
4
5
6
7
020
030
040
050
060
070
200
Data storage has two categories. They are:
Bit/Word storage
File storage
Bit/Word Storage
Bit/word storage addresses can be located in all unused areas of the data
table excluding the input image table and processor work areas. Data table
addresses for bit and word storage should be chosen carefully to optimize
memory use.
The following recommendations for bit and word storage should be
considered:
Unused data table words in T/C areas can be used for bit/word storage.
To conserve memory, use both the accumulated and preset value words
for storage.
3.4.7
Timer/Counter Assignments
3.4.8
Data Storage Assignments