Siemens SIMATIC S5-100U, System Manual

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STEP 5 Operations S5-100U
Load Operation
During loading, information is copied from a memory area, e.g., from the PII, into ACCU 1.
The previous contents of ACCU 1 are shifted to ACCU 2.
The original contents of ACCU 2 are lost.
Example: Two consecutive bytes (IB7 and IB8) are loaded from the PII into the accumulator.
Loading does not change the PII (see Figure 8-2).
Figure 8-2. Execution of the Load Operation
Byte a
Byte c
L IB8
L IB7
Information
from the PII Lost
information
0 IB7
ACCU 2 ACCU 1
Byte b
Byte d IB7
Byte d Byte c Byte a
Byte b IB7 0
Byte b
Byte a
0 IB8 IB
Transfer Operation
During transfer, information from ACCU 1 is copied into the addressed memory area, e.g., into the
PIQ.
This transfer does not affect the contents of ACCU 1.
Example: Figure 8-3 shows how byte a, the low byte in ACCU 1, is transferred to QB5.
Figure 8-3. Transferring a Byte
T QB5
Information
in the PIQ Lost
information ACCU 2 ACCU 1
Byte d Byte c Byte a
Byte d
Byte b
Byte c Byte a Byte a Byte b
Previous value
of QB5
8-12
EWA 4NEB 812 6120-02b