Siemens S5-135U/155U appendix Via IB, Off Ir-G Int

Digital Input/Output Modules

Only the flag word (FW) 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 the input circuit 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 IB 0:

Step

Action

1

2

3

4

Insert jumpers X3 and X4

Set switch row S1 to Off.

Set bit 0 on switch row S2 to On, and all other switches to Off.

Set switch row S3 to choose whether the interrupt is to be initi- ated with a positive-going (leading) or negative-going (trail- ing) edge. The setting of a pair of switches applies to an entire byte.

		S1
	0	IR-A
	1	IR-B
	2	IR-C
	3	IR-D
	4	IR-E
	5	IR-F
:OFF	6	IR-G
:ON	7	INT

	S2
0	Bit 0
1	Bit 1
2	Bit 2
3	Bit 3
4	Bit 4
5	Bit 5
6	Bit 6
7	Bit 7

	S3
0	}	Byte 3
1
2	}	Byte 2
3
4	}	Byte 1
5
6	}	Byte 0
7

Byte 0: Positive-Going Edge

Byte 1: Negative-Going Edge-

Byte 2: Both Edges

Byte 3: No Process Interrupt

Figure 8-5 Switch Settings for Operation with Process Alarm via IB 0 (Example)

System Manual	8-11
C79000-G8576-C199-06