NORD Drivesystems BU0550 - Manual (Page 21)

3 AWL (Instruction List, IL)
BU 0550 GB-0813 21
3.1.3 Comments
It is advisable to provide the sections of the program with comments in order to make the PLC program
understandable at a later date. In the application program these comments are marked by starting with the
character sequence "(*" and finishing with "*)" as shown in the following examples. These comments are not
communicated to the frequency inverter.
(* Comment about a program block *)
LD 100 (* Comment about a command *)
ADD 20
3.1.4 Jump marks
Entire sections of the program can be skipped with the aid of the operators JMP, JMPC or JMPCN (see
Section 3.3). A jump mark is given as the target address. With the exception of umlaut characters and "ß"
they may contain all letters, the numbers 0 to 9 and underscores. Other characters are not permitted. The
jump mark is terminated with a colon. This may stand on its own. There may also be further commands after
in the same line after the jump mark.
Possible variants may appear as follows
Jump mark:
LD 20
This_is_a_jump_mark:
ADD 10
MainLoop: LD 1000
A further variant is the transfer of a jump mark as a variable. This variable must be defined as type
LABLE_ADDRESS in the variable table, then this can be loaded into the variable 'jump marks'. With this, a
status machine can be created very simply, see below
JMP Address_Var
Address_1:
LD Address_2
ST Address_Var
JMP End
Address_2:
LD Address_3
ST Address_Var
JMP End
Address_3:
LD Address_1
ST Address_Var
End: