Lenze PLC Designer PLC Designer (R3-1) - Manual (Page 1107)

L-force | PLC Designer
Devices
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DMS 4.1 EN 03/2011 TD29 1105
If everything has been configured correctly, all I/O compound modules are marked
with a green circle in the device tree after the user goes online and starts the PLC.
In the event of an error, i.e. the configuration does not match the physical
arrangement, the I/O compound modules are marked with a red circle.