Siemens SITRANS FUS060 Operating Instructions Manual page 24

Description
3.5 PROFIBUS communication
The maximum number of devices that can be connected to a bus line depends on their current
consumption and the respective application conditions. When operating in an area where there
is no risk of explosion, the couplers/links can feed up to 400 mA into the bus.
Use in hazardous areas
When operating in explosion risk areas, the intrinsic safety is only guaranteed when the
maximum power fed into the bus does not exceed certain voltage and current values.
These are normally:
• Current IS < 128 mA
• Voltage U0 <15 V
Intrinsically safety
Only certified supply units (DP/PA couplers or DP/PA links) may be used to feed the intrinsically
safe PROFIBUS. See the EC Type Examination Certificate for requirements.
The number of devices which can be connected to a bus line is given by the total of maximum
current consumptions of the connected devices (>= 10 mA per device is the standard).
A current reserve should be planned for safety, otherwise there is a risk that a defective device
overloads the bus with its increased current consumption and the power supply and
communication with all unaffected users could collapse. The power reserve quantity depends
on the current increase in the event of an error specified by the manufacturer.
Note
The electronic current limiter installed additionally in the device ensures that the current does
not increase by more than 5 mA even when a device is defective.
Note
Every device has its own address to distinguish between the connected process devices. The
address setting is described in the Commissioning (Page 41).
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WARNING
WARNING
SITRANS FUS060 with PROFIBUS PA
Operating Instructions, 09/2021, A5E02225054-AD