Index Registers (I0 To Id) (For Fp2, Fp2Sh And Fp10Sh) - Panasonic FP-E Programming Manual

Relays, Memory Areas and Constants

1.3.11 Index Registers (I0 to ID) (for FP2, FP2SH and FP10SH)

Function of index registers (I0 to ID)
Index registers are used for indirect specification of values to addresses and operands
in relays and memory areas.
Changing an address or a constant using an index register value is called "index
modification".
There are a total of 14 index registers which can be used with the FP2, FP2SH and
FP10SH, consisting of I0 to I9 and IA to ID.
With the FP2SH/FP10SH, because there are bank areas for index registers, changing
the bank enables 14 points x 16 banks = 224 points of index registers available for use.
Cautions when using index registers
An index register can not be modified with an index register.
I0I0, I1I1
An index register can be modified using a different index register.
Available: I0IA, Not available: I0I0
If the result of address modification overflows the memory area, an operation error will
result.
When the address resulting from modification is negative or a large number.
When a 32−bit constant is modified, the specified index register number and the
following index register number are used in combination to handle the data as a 32−bit
data.
Higher 16−bit area
Contents of In+1
The results of modification will be 32−bit data.
Note
When 32−bit constants are being modified, ID should not be
specified.
For the FP2/FP2SH/FP10SH, if the Initialize/Test switch is set to the upper side (the
Initialize side) in the PROG mode, index registers I0 to ID are cleared to 0.
Note
With the FP2SH/FP10SH, system register 4 can be set in such a
way that these are not cleared to 0 even if the Initialize/Test
switch is set to the upper side.
The bank switching function for index registers can be used on the FP2SH/FP10SH.
This function is not provided in the FP2.
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Lower 16−bit area
Contents of In