3.5
STEP 5 Operations with Examples
A STEP 5 operation consists of the operation and an operand. The
operation specifies what the CPU is to do (operation). The operand
specifies with what an operation is to be executed.
STEP 5 operations can be divided into the following groups:
••
basic operations (can be used in all logic blocks),
••
supplementary operations,
••
executive operations (can only be used in FB/FX function blocks),
••
semaphore operations (can only be used in FB/FX function blocks).
Accumulators as working
registers
The CPU 948 has four accumulators, ACCU 1 to ACCU 4. Most
STEP 5 operations use two 32-bit registers (ACCU 1 and ACCU 2) as
the source of operands and the destination for results.
The STEP 5 operation to be carried out affects the accumulators, e.g.:
••
ACCU 1 is always the destination in load operations. A load
operation shifts the old contents of ACCU 1 to ACCU 2 (stack
lift). Accumulators 3 and 4 are not changed by any load operations.
1)
analogous for ACCU 2 to ACCU 4
ACCU-1-H
High byte
Low byte
High byte
Low byte
ACCU 1
1)
High word
Low word
31
24 23
16 15
8 7
0
ACCU-1-HL
ACCU-1-LH
ACCU-1-LL
ACCU-1-L
ACCU-1-HH
STEP 5 Operations with Examples
CPU 948 Programming Guide
C79000-G8576-C848-04
3 - 15
Summary of Contents for CPU 948
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Page 72: ...Data Blocks CPU 948 Programming Guide 2 42 C79000 G8576 C848 04 ...
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Page 200: ...Contents CPU 948 Programming Guide 5 2 C79000 G8576 C848 04 ...
Page 308: ...Contents CPU 948 Programming Guide 7 2 C79000 G8576 C848 04 ...
Page 324: ...Examples of Parameter Assignment CPU 948 Programming Guide 7 18 C79000 G8576 C848 04 ...
Page 326: ...Contents CPU 948 Programming Guide 8 2 C79000 G8576 C848 04 ...
Page 370: ...Addressable System Data Area CPU 948 Programming Guide 8 46 C79000 G8576 C848 04 ...
Page 372: ...Contents CPU 948 Programming Guide 9 2 C79000 G8576 C848 04 ...
Page 486: ...Contents CPU 948 Programming Guide 11 2 C79000 G8576 C848 04 ...
Page 522: ...PG Functions via the S5 Bus CPU 948 Programming Guide 11 38 C79000 G8576 C848 04 ...
Page 524: ...Contents CPU 948 Programming Guide 12 2 C79000 G8576 C848 04 ...
Page 538: ...Contents CPU 948 Programming Guide 13 2 C79000 G8576 C848 04 ...
Page 546: ...List of Key Words CPU 948 Programming Guide Index 6 C79000 G8576 C848 04 ...