Index Register (X Register) - HEIDENHAIN TNC 426 PB/M Technical Manual

Table of Contents

7.8 INDEX Register (X Register)

You can use the index register for:

Data transfer

Buffering results

Indexed addressing of operands

The index register is 32 bits wide. However, the TNC uses only the lower 16

bits for indexed addressing.

You can use the X register anywhere in the program. The TNC does not check

whether the current content is valid. Exception: During indexed write

accessing the TNC checks whether the amount of available address space is

Example: = B100[X]

If the permitted addressable storage is exceeded, the TNC issues a blinking

error message: PLC: index range incorrect. Acknowledge the error

message by pressing the END key. After restarting the TNC you must not

acknowledge the POWER INTERRUPTED message. Go into the PLC editor,

where you will be shown the error line.

At the beginning of the PLC cycle the TNC sets the index register to 0.

Assign the index register a defined value before using it in your program.

The following addresses are valid:

of the n-th string

The types "S", K, and K$ cannot be indexed.

If you address S#Dn[X] or S#En[X], the TNC loads the sequence

<SUB>Dnnn or <SUB>Ennn in the string accumulator, where nnn is the

modified string number.

Operand number = n+X

Operand number = n+2*X

Operand number = n+4*X

Content of index register =

String number = n+X

Dialog text number = n+X

Error text number = n+X

ASCII code +X

Substring from X-th character

HEIDENHAIN Technical Manual TNC 426, TNC 430