Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 96)

Programming DH and DH+
Message Procedures
Chapter 6
6-5
You cannot use certain words and character combinations as symbols
because they are reserved for special uses in message procedures. The
reserved words are:
CREATE
DELETE
ERROR
EXIT
GOTO
IF
ON_ERROR
STOP
PROT
UNPRO
You also cannot use any abbreviated form of the above words. For
example, you cannot use the single letter C as a symbol because it is an
abbreviation of the word CREATE. Similarly, PRO is an invalid symbol.
The two types of symbols are (Figure 6.2):
user symbols
system symbols
Figure 6.2
Types of Symbols
User Symbol
Generate this symbolic
value through the
assignment command.
Symbol
System Symbol
Generate this symbol
with the Edit command
(for a procedure name)
or a Create command
(for a symbolic address).
Procedural
Applies only to the
procedure in which it is
generated.
Interprocedural
Applies to the procedure
in which it is generated
plus any other procedure
nested together with that
procedure.
Procedure Name
Applies to a single
procedure or other
procedures nested
together within that
procedure.
Global
Applies to any context.
Symbolic Address
Can be used anywhere
in place of a logical
address.
Local
Applies only to the
context in which the
symbol is generated.
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