Siemens S5-135U/155U appendix Program is independent of the slot, Start Address

Digital Input/Output Modules

On Setting	Addressing Switch
(Switch Pressed)

Address (Decimal)

Labeling Field for the Module Address and Marked Switch Settings

128	64	32	16	8	4	2	1
ADB7	ADB6	ADB5	ADB4	ADB3	ADB2	ADB1	ADB0

Binary Significance of the Address Bit

Address Bit

	Figure 8-7	Labeling of the Addressing Switch (Extract from Module Labeling)
	The address byte under which the module is referenced by the STEP 5
	program is independent of the slot.
Start Address	For modules with 16 or 32 inputs or outputs, i.e. 2 or 4 bytes, only the lowest
	address (start address) is set for the first byte. The addresses of the following
	bytes of the same module are decoded on the module.

If, for example, the address 20 is set for a 16-bit module (2 bytes), the following address 21 is decoded internally and is no longer available. The next free address would be 22.

For a 32-bit module (4 bytes) with start address 20, addresses 21, 22 and 23 would be decoded internally. The next free address would be 24.

Addresses already assigned must not be set again.

However, digital input and output modules may be given the same address because they are referenced by different commands in the user program.

System Manual	8-15
C79000-G8576-C199-06