Siemens SIMATIC S5-115U, Руководство пользователя

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S5-115U Manual Addressing/Address Assignments
6 Addressing/Address Assignments
In order to be able to access input/output modules, these modules must be assigned addresses.
6.1 Address Structure
Digital modules generally are addressed by bit, analog modules by byte or word. Consequently,
their addresses have different formats.
6.1.1 Digital Module Addresses
One bit represents a channel on a digital module. You must therefore assign a number to each bit.
When numbering, note the following:
• The CPU program memory is divided into different address areas (see Section 6.3).
• Number individual bytes consecutively in relation to the start address of the relevant address
area.
• Number the eight bits of each byte consecutively (0 to 7).
Figure 6-1 shows the format of a digital address:
Bit No. (Channel Number)
Byte No.
0 . 5
Figure 6-1. Format of a Digital Address
6.1.2 Analog Module Addresses
Each channel of an analog module is represented by two bytes (=one word).
An analog channel address is thus represented by the number of the high-order byte.
6.2 Slot Address Assignments
You can establish addresses for S5-115U modules in the following two ways:
• Fixed Slot Addressing
Each slot has a fixed address under which you can reference the module plugged into that
slot.
• Variable Slot Addressing
The user can specify an address for each slot.
Fixed slot and variable slot addresses are relevant only for modules of block design. The addresses
of intelligent I/O modules and modules of ES 902 design (S5-135U/155U) are set on the modules
themselves. In this case, the address need not be set on the IM 306.
EWA 4NEB 811 6130-02b
6-1