
Parker Hannifin
40 Programmer’s Guide
NOTE: The memory organization differs for each controller—for
more information, see the section titled Memory
Organization in the ACR Command Language Reference.
System and Program Memory Levels
Memory is allocated at two levels, the system level and program
level:
System
At the SYS prompt, you can allocate memory for the following:
• Programs: The factory default divides memory equally among
programs 0-7 (factory default is 512K total).
• PLC Programs: The factory default provides no memory
allocated to PLC programs.
• Communication Stream Buffers: The stream buffers are
optimized for communication (factory default is 256 bytes).
Most applications do not require adjustments to the buffer size,
as the controllers use flow control.
If you are losing data, you can adjust the stream buffer. As
each application is different, incrementally increase the buffer
size to determine the best setting for your application.
Increasing the buffer allows the front-end software to perform
smoothly while the controller manages data in the
background.
• Global Variables: The factory default provides no memory
allocated to global variables. There are 4096 user parameters
available (64-bit floating point); the range is P0-P4096. For
example, if you dimension memory for 100 global variables,
then you can use P0-P99.
• Aliases: The factory default provides no memory allocated to
aliases. Once you define the number of aliases, you can use
the #DEFINE command to set them up.
Program
At the PROG prompt, you can allocate memory for the following:
• Local Variables: The factory default provides no memory
allocated to local variables. After allocating memory, these
items are available only within the specified program.
• Strings: The factory default provides no memory allocated to
strings. After allocating memory, these items are available only
within the specified program.
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