Load And Transfer Operations - Siemens SIMATIC S5-115U User Manual

Simatic s5 series cpu 941-7ub11 cpu 942-7ub11 cpu 943-7ub11 and cpu 943-7ub21 cpu 944-7ub11 and cpu 944-7ub21
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STEP 5 Operations
8.1.3

Load and Transfer Operations

Use load and transfer operations to do the following:
exchange information between various operand areas
prepare times and counts for further processing
load constants for program processing.
Information flows indirectly via accumulators (ACCUM 1 and ACCUM 2). The accumulators are
special registers in the CPU for temporary storage. In the S5-115U they are each 16 bits long. The
accumulators are structured as shown in Figure 8-1.
15
High
You can load and transfer permissible operands in bytes or words. For exchange in bytes,
information is stored right-justified, i.e., in the low byte.
The remaining bits are set to zero.
You can process the information in the two accumulators using various operations.
Load and transfer operations are executed independently of condition codes. Execution of these
operations does not affect the condition codes.
You can program load and transfer operations graphically only in combination with timer or
counter operations; otherwise you can represent them only in STL form.
Table 8-3 provides an overview of the load and transfer operations. Examples follow the table.
8-10
ACCUM 2
8
7
0
Low
Byte
Figure 8-1. Accumulator Structure
ACCUM 1
15
8
7
High
Low
Byte
EWA 4NEB 811 6130-02b
S5-115U Manual
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