Siemens S5-135U/155U System Manual page 439

Note
The start address of the analog module must be a multiple of the double
channel number.
8 channels : 0, 16, 32, 48, ... 240
16 channels : 0, 32, 64, 96, ... 224
If one of the inputs or outputs (Channel 0 to 7 or 0 to 15) of a module is to be
addressed, the relevant subaddress must be specified in the program.
The subaddress of the input or output, based on the start address of the
module, is given by:
Example:
Analog input module with 8 or 16 inputs
The address is the sum of the significances set with the individual coding
switches.
A module with 8 or 16 inputs (Channel 0 to 7 or 0 to 15) and start address
160 reserves the address range from
In this example, the next free address for another module is 176 or 192.
With the 465 analog input module, the size of the address range depends on
the number of channels set (8 or 16).
Addresses already assigned must not be set again.
System Manual
C79000-G8576-C199-06
Start address + 2 x channel no. = subaddress
160 = 128 + 32 = 2
On Setting
(Switch Pressed)
160 to address 160 + 7 x 2 = 174
160 to address 160 + 15 x 2 = 190
Analog Input/Output Modules
7 5
+ 2
IB 160
9-57