Siemens S5-135U/155U - Manual (Page 322)

8-10
System Manual
C79000-G8576-C199-06
S1
3 3 3 Bit 3 IR-D
4 4 4 Bit 4 IR-E
5 5 5 Bit 5 IR-F
6 6 6 Bit 6 IR-G
7 7 7 Bit 7 INT
0 0 0 Bit 0 IR-A
1 1 1 Bit 1 IR-B
2 2 2 Bit 2 IR-C
Process Interrupt via IR-C
Byte 0: Positive-Going Edge
Byte 1: Negative-Going Edge-
Byte 2: Both Edges
Byte 3: No Process Interrupt
Byte 0
Byte 1
Byte 2
Byte 3
S2 S3
}
}
}
} : OFF
: ON
Figure 8-4 Switch Settings for Operation with Process Alarm via Interrupt (Example)
In this mode, a process alarm is initiated via input byte IB 0. This mode is
only possible in conjunction with a CPU 948 in single-processor operation.
To operate the 432 digital input module with process alarm via IB 0, you can
insert it at any I/O slot.
When you use the module in the CC, you must not set any other input
module to address 0 (i.e. neither in the normal (P) nor in the extended (O)
area).
If you use the module in an EU which is addressed in the normal area, you
must not set any other input module in the EU to address 0 in the normal
area.
So that the module can initiate a process alarm for a change of logic state, the
alarm must be processed by an alarm routine (alarm OB) in the user program,
with automatic acknowledgement of the alarm. To avoid loss of an alarm, it
must not be possible for the alarm OB to be interrupted by process alarms.
The CPU must process the process alarms with level triggering (see
Programming Guide of the CPU).
Example:
Program the following in the alarm OB which you have preset with byte IB 0
and switch S2:
L PW128 (load I/O word)
T FW0 (transfer flag word)
L PW130 etc.
T FW2
Operation with
Process Alarm
via IB 0
Scanning the
Process Inputs
Digital Input/Output Modules