Siemens S5-100U User Manual page 167

Simatic s5 programmable controller
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STEP 5 Operations
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).
Lost
information
Byte d
Byte c
Byte b
Byte a
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.
ACCU 2
Byte d
Byte c
Byte d
Byte c
8-12
ACCU 2
Byte d
Byte c
Byte b
Byte a
0
IB7
Figure 8-2. Execution of the Load Operation
ACCU 1
Byte b
Byte a
Byte b
Byte a
Figure 8-3. Transferring a Byte
ACCU 1
Byte b
Byte a
0
IB7
0
IB8
Information
in the PIQ
T QB5
Byte a
S5-100U
Information
from the PII
L IB7
IB7
L IB8
IB
Lost
information
Previous value
of QB5
EWA 4NEB 812 6120-02

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