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S5-95F
Note
Direct accessing of the external I/Os is permissible only in OB13 (see section 6.7). If you
program direct accesses to external I/Os in OB1, OB2 or OB3, the S5-95F reacts with a
corresponding error message and STOP.
6.6.4
Direct Access to External I/Os
External I/Os can be directly accessed only in OB 13.
Please note that the operation L PW 31 loads only the I/O byte 31 into the high byte of accu 1; the
low byte is loaded with 0. The operation T PW 31 affects only byte 31.
6.7
Interrupt Process Image Tables and Time-Controlled Program
Processing in OB13
The S5-95F makes time-controlled program processing possible. OB13 must be programmed for
this purpose. OB13 is called up periodically. You can determine the call up interval.
Within time-controlled program processing, you can use the operand identifiers, "PB", "PY", and
"PW", not only with the onboard I/Os, but also with the external I/Os.
Load and transfer operations act as direct access (see section 6.6.3) to the onboard I/Os if these
operand identifiers are used.
However, if the statement is in reference to the external I/Os, the programmable controller does not
directly access the external I/O modules. It accesses the interrupt process image tables.
•
The interrupt process image tables are used only in time-controlled program processing.
•
The interrupt process image tables and the "normal" process image tables have an identical
structure.
•
The interrupt process image input tables (interrupt PII) and the interrupt process image output
tables (interrupt PIQ) each have an area of 128 bytes in RAM.
Note
Access to the interrupt process image (I/O) tables can only be byte-by-byte or word-by-
word. 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.
6.7.1
Accessing the Interrupt PII
•
The interrupt PII can only be accessed within time-controlled program processing.
•
The data from inputs is read into the interrupt PII only at the beginning of time-controlled
program processing.
The data is available exclusively to the time-controlled program for evaluation.
EWA 4NEB 812 6210-02
Addressing
6-13
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