Siemens SIMATIC S5-95F, Manual

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Addressing S5-95F
6.6.1 Accessing the Process Image Input Table (PII)
During a data cycle, data is read into the process image input table (PII) from input modules.
This data is available to the control program for evaluation in the next program processing cycle.
Access to the PII is expressed by the operand identifiers "I", "IB", or "IW" in a statement in the
control program.
The letter "L" identifies the "Load" operation (see Chapter 8). The letter "A" identifies the "AND
logic" operation (see Chapter 8).
Note
Failsafe external I/Os may be accessed only via even-numbered byte addresses. Word-
by-word accessing of failsafe external I/Os is rejected by the S5-95F with an error
message.
Figure 6-6. Accesses to the PII
• Bit-by-bit reading "I <bit address>"
Example: Reading in the signal state of
channel 2 of a 4-channel digital input module
in slot 2
A I 2.2
• Byte-by-byte reading "IB <byte address>"
Example: Reading in the signal states of all
channels of an 8-channel digital input module
in slot 12
• Word-by-word reading "IW <word address>"
Example: Reading in the analog value of channel
3 of a 4-channel analog input module in slot 4
Bit number
PII
Byte 2
Byte 12
Byte 102
Byte 103
7 6 5 4 3 2 1 0
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High byte
0 15
L IB 12
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ACCU 1
Low byte
0 15
ACCU 1
High byte Low byte
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a a a a a a a a a a a a a a a a a a a a a a
L IW 102
6-10
EWA 4NEB 812 6210-02