Configuring Hardware and Communication Connections STEP 7.pdf

2.3.9 Assigning I/O Addresses
Requirements
Procedure
Configuring Central Racks
STEP 7 assigns input and output addresses when modules are placed in the
configuration table. This means every module has a start address (address of the
first channel); the addresses for the remaining channels are based on this start
address.
• The module is inserted in a central rack or expansion rack and the CPU must
permit free address assignment.
• The module is inserted in a DP slave or the module is a DP slave (compact DP
slave).
1. Double-click on the row of the rack containing the module whose start address
you wish to set, or select the module and select the Edit > Object Properties
menu command.
2. Select the "Addresses" tab.
3. Change the default start address.
Note
For modules within a local bus segment, formed by a function module (S7-300) or
for special function modules (S7-400), you have to assign a further start address.
In addition to the start address for the CPU, the module then has a start address
for the FM. In the overall view of the configuration table, the start address from the
point of view of the FM is always displayed in this case.
Displaying the Address Overview
You can display the input and output addresses already used and any address
gaps as follows:
1. Open the station whose addresses you want to display.
2. Select the menu command View > Address Overview.
3. In the "Address Overview" dialog box, select the module whose assigned
inputs and outputs you want to display (for example, CPU).
4. If required, you can filter the display by address type (for example, input
addresses only).
The address areas "Inputs" and "Outputs" are displayed with locations for the
modules (e.g. master system no., PROFIBUS address for PROFIBUS DP, rack,
slot, interface submodule slot). Input addresses with the length 0 (for example,
addresses of interface modules) are marked with an asterisk (*).
Configuring Hardware and Communication Connections with STEP 7
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