Siemens S5-135U/155U System Manual page 321

Operation with
To operate the 432 digital input module with process alarm via an interrupt,
Process Alarm via
you must either operate it in the CC where only certain slots have interrupt
Interrupt lines (see Chapter 4), or in an interrupt-capable EU connected to the CC with
IM 307 - IM 317 interfacing (see also the IM 307 - IM 317 manual). In the
CC, you may only operate the module in this mode at slots with an interrupt
line (interrupt source).
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).
Scanning the
Example:
Process Inputs
Program the following operations in the corresponding alarm OB:
Only the flag word may be accessed during the cyclic program.
Accessing the I/O bytes in the process image will result in alarm loss.
Addressing of the module must therefore be above address 127. Double
accessing of I/O bytes, even from different CPUs, is not permissible (alarm
loss).
The four I/O bytes of a module must be scanned successively and in
ascending order. The scanning of byte n inhibits all input circuits of the
module, and the scanning of byte (n + 3) enables them again.
Settings on the
Make the following settings on the module to operate it with a process alarm
Module
via interrupt:
Step
1
2
3
4
System Manual
C79000-G8576-C199-06
L PW132 (load I/O word)
T FW10 (transfer flag word)
L PW134 etc.
T FW12
Action
Open jumper X4 and close jumper X3.
Set the interrupt line at switch row S1: the switch relating to the
desired interrupt line should be set to On. Set all other switches
to Off. You can set the same interrupt line on several modules.
Set switch row S2 to Off.
Set switch row S3 to choose whether the interrupt is to be initi-
ated with a positive-going (leading) or negative-going (trailing)
edge. The setting of a pair of switches applies to an entire byte.
Digital Input/Output Modules
8-9