Safety instructions   
2.5 Information on I/O devices 
  SIMATIC IPC677E 
30  Operating Instructions, 04/2019, A5E45117996-AA 
2.5  Information on I/O devices 
 
Fault caused by I/O devices 
The connection of I/O devices can cause faults in the device. 
The result may be personal injury and damage to the machine or plant. 
•  Only connect I/O devices which are approved for industrial applications in accordance 
with EN 61000-6-2 and IEC 61000-6-2. 
•  I/O devices that are not hotplug-capable may only be connected after the device has 
been disconnected from the power supply. 
 
Damage through regenerative feedback 
Regenerative feedback of voltage to ground by a connected or installed component can 
damage the device. 
Connected or built-in I/Os, for example, a USB drive, are not permitted to supply any 
voltage to the device.  
Regenerative feedback is generally not permitted. 
 
Note 
Checking the regenerative feedback
 
measuring the counter emf, remember the following: 
  The computer in question must be turned off and the power supply connector must be 
plugged in. 
  During the measurement, all cables from the plant to the computer should be connected. 
  All other components in the plant must be active.