Siemens S5-135U/155U appendix Scanning, Process Inputs, Settings on, Via interrupt

Digital Input/Output Modules

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

Interruptlines (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:
	L	PW132	(load I/O word)
	T	FW10	(transfer flag word)
	L	PW134	etc.
	T	FW12

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

Action

1

2

3

4

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.

System Manual	8-9
C79000-G8576-C199-06