45
CP1L-EL/EM CPU Unit Operation
Section 2-3
• When the power supply is turned ON, data is transferred from the
Memory Cassette to the built-in flash memory and RAM. Data can also
be transferred from the Memory Cassette to the built-in flash memory
and RAM using the CX-Programmer.
User Program
The user program consists of up to 288 tasks, including interrupt tasks. Each
task is programmed from the CX-Programmer and then transferred to the
CPU Unit.
There are two types of tasks: cyclic tasks and interrupt tasks. Cyclic tasks are
executed once each cycle and interrupt tasks are executed only when the
interrupt conditions are met. There can be up to 32 cyclic tasks and up to 256
interrupt tasks. Cyclic tasks are executed in the order of the task numbers.
Instructions programmed in the tasks are executed in order from the first
instruction and then I/O memory is refreshed. When all cyclic tasks have been
executed, I/O refreshing with PLC Units is performed and then the cyclic tasks
are executed again starting from the one with the lowest task number. This is
called the cyclic scan method.
I/O Memory
The I/O memory area is a RAM area read and written by the user. Some parts
of the I/O memory are cleared when the power is interrupted. Other parts are
maintained. There are parts that used for data exchange with PLC Units and
parts that are used internally.
There are two ways to refresh the parts of I/O memory used for data
exchange with PLC Units: Once each program execution cycle and immedi-
ately when needed when executing specific instructions.
Parameter Area
In addition to the I/O memory used as instructions operands by the user, there
is also a separate memory area that can be manipulated only from the CX-
Programmer. This area, called the parameter area, contains the following.
• PLC Setup
• Routing tables
PLC Setup
The PLC Setup contains configuration parameters that can be set by the user
to define the basic specifications of the CPU Unit. Included are serial port set-
tings, a minimum cycle time setting, and other parameters. For details, refer to
the CX-Programmer Operation Manual.
Routing Tables
Tables specifying the communications paths from the Communications Units
on the local PLC to remote PLCs connected on other networks must be regis-
tered in all the CPU Units in network PLCs to send and receive data between
networks. These tables are called the routing tables. The routing tables con-
sist of the relay network table and local network table.
Routing tables are created from the CX-Programmer or Support Software for
Communications Units (e.g., CX-Integrator) and then transferred to each CPU
Unit.
Summary of Contents for CP1L-EL20DR-D
Page 3: ...CP1L EL20D CP1L EM30D CP1L EM40D CP1L EL EM CPU Unit Operation Manual Produced July 2017...
Page 4: ...iv...
Page 10: ...x...
Page 22: ...xxii...
Page 34: ...xxxiv Software Licenses and Copyrights 7...
Page 192: ...158 Trial Operation and Debugging Section 5 3...
Page 250: ...216 Automatic Clock Adjustment and Specifying Servers by Host Name Section 6 7...
Page 666: ...632 Trouble Shooting Section 11 7...
Page 696: ...662 Standard Models Appendix A...
Page 805: ...771 Connections to Serial Communications Option Boards Appendix F Connecting to Unit...
Page 806: ...772 Connections to Serial Communications Option Boards Appendix F...
Page 836: ...802 PLC Setup Appendix G...
Page 838: ...804 TCP Status Transitions Appendix H...
Page 840: ...806 Ethernet Network Parameters Appendix I...
Page 842: ...808 Buffer Configuration CP1L EL EM Appendix J...
Page 844: ...810 Ethernet Specifications Appendix K...
Page 851: ...Index 817 work words 118 write protection 447...
Page 852: ...818 Index...
Page 854: ...820 Revision History...
Page 855: ......