Potential Levels

The I/O system is divided internally into the following potential groups.

• System Level
• This potential group encompasses all the system-side electronics and includes the system supply and local bus signals among other things.
• Field Level
• This potential group contains the field-side power supply and I/O signals. The node structure can be divided into different sections with supply and segment modules. Different field potentials can be used in the individual sections.
• Fieldbus
• This potential group contains the signals of the corresponding fieldbus interface. The voltage and current levels depend on the fieldbus standard used.
• Functional Ground
• To discharge EMC interference, the system power supply, the field power supply and the I/O signal inputs and outputs are capacitively coupled within the module to the functional ground via the DIN-rail contacts.

I/O modules with dangerously active voltages on the field level are safely isolated from the system level. Functional isolation from the system level is provided for I/O modules with SELV/PELV voltages on the field level.

You can find product-specific information on “Isolation” in the technical data of the corresponding & Product Manual.

Example Potential Groups/Isolation with Electrically Isolated Power Supply Infeed