Technical data

Programming with STEP 7
Manual, 05/2010, A5E02789666-01 401
18 Establishing an Online Connection and Making CPU
Settings
18.1 Establishing Online Connections
An online connection between programming device and programmable logic controller is needed to
download S7 user programs/blocks, upload blocks from the S7 programmable controller to the
programming device, and for other activities:
• Debugging user programs
• Displaying and changing the operating mode of the CPU
• Displaying and setting the time and date of the CPU
• Displaying module information
• Comparing blocks online and offline
• Diagnosing hardware
To establish an online connection, the programming device and programmable logic controller
must be connected via a suitable interface (for example, multipoint interface (MPI)). You can then
access the programmable controller via the online window of the project or the "Accessible Nodes"
window.
18.1.1 Establishing an Online Connection via the "Accessible Nodes" Window
This type of access enables you to access a programmable logic controller quickly, for test
purposes, for example. You can access all the accessible programmable modules in the network.
Select this method if no project data about the programmable controllers are available on your
programming device.
You open the "Accessible Nodes" window using the menu command PLC > Display Accessible
Nodes. In the "Accessible Nodes" object, all the nodes accessible in the network are displayed
with their address.
Nodes that cannot be programmed with STEP 7 (such as programming devices or operator panels)
can also be displayed.
The following additional information can also be shown in parentheses:
• (direct): This node is directly connected to the programming device (programming device or
PC).
• (passive): Programming and status/modify via PROFIBUS DP is not possible with this node
• (waiting): This node cannot be communicated with because its configuration does not match
the rest of the settings in the network.