HEIDENHAIN MANUALplus 620 Technical Manual page 1724

Operand
declaration
Logical
comparisons during
string processing
1724
The "S" operands are to be used only for string processing. You can target the
following addresses with the various arguments:
Addressing string memory: After the operand designation, specify the
number of the desired memory (S0 to S99).
Symbolic operands (B/W/D operands) can now be used for indexed access
to the string operands "S" or the PLC error and dialog files.
Examples:
#define offset D100
...
L S2[offset]
= S8
...
or
S#D900[NP_W1022_Module_error_status]
Address part of a string: Use the address Sn^X (see INDEX Register). The
control addresses the substring beginning with the X-th character of the
specified string.
Effective immediately, addressing with symbolic operands is also possible:
Sn^symbolic operand (B/W/D operand).
Immediate string: You can also enter a string directly in the PLC program.
The text string, which may contain a maximum of 128 characters, must be
indicated by quotation marks.
Example: "Coolant 1 on"
Texts from the PLC error message file or from the PLC dialog file: By
specifying the line number you can read texts from the active error message
file or dialog file: PLC-ERROR: S#Exx xx: Line number from the PLC error
message file (0 to 999)
PLC-DIALOG: S#Dxx xx: Line number from the PLC dialog file (0 to 999).
Enter the string #Exx or #Dxx in the argument <arg> of the string command.
The control then saves a 5-byte-long string <SUB> E0xx or <SUB> D0xx
(<SUB> = ASCII <SUB>) in the accumulator. Instead of this string, the
control reads the line xx of the active error message or dialog file on the
screen.
Enter an ASCII character in the string. Define the ASCII character through its
code: S#Axxx
Use the following procedure to compare two strings, depending on the
argument:
If you compare string memories or immediate strings, the control checks
both strings character by character. After the first character that does not
fulfill the condition of comparison, the control resets the logic accumulator.
The control does not check the remaining characters. During a comparison,
the control always uses the significance of the characters from the ASCII
table. This results, for example, in:
A < B
AA > A
If you have entered PLC error messages or PLC dialog texts in the
argument, the control compares the position in the error-message file or
dialog file (0 to 999), but not the actual text as in an immediate string.
The processing times depend on the length of the strings.
HEIDENHAIN Technical Manual MANUALplus 620