Siemens SIMATIC S5-115U, User Manual

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STEP 5 Operations S5-115U Manual
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.
ACCUM 2 ACCUM 1
Low High
Byte
Low High
Byte
15 8 7 0
15
8 7
0
Figure 8-1. Accumulator Structure
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
EWA 4NEB 811 6130-02b