Interference On Rs485 Communication - Kruger Ecowatt K320 Series Operation Manual

Ecowatt Drive K320 series
®
Note:
When a decoupling capacitor is required, add it to the terminal of the device connected

to the sensor. For example, if a thermocouple is to transmit signals of 0 to 20 mA to a
temperature meter, the capacitor needs to be added on the terminal of the temperature
meter; if an electronic ruler is to transmit signals of 0 to 30 V to a PLC signal terminal,
the capacitor needs to be added on the terminal of the PLC.
If a large number of meters or sensors are disturbed. It is recommended that you

configure an external C2 filter on the input power end of the VFD. For models of filters,
see the filter model selection section D.7.2 Filter model selection.

7.7.2 Interference on RS485 communication

Interference phenomenon
The interference described in this section on 485 communication mainly includes
communication delay, synchronization failure, occasional power-off, or complete power-off
that occurs after the VFD is started.
If the communication cannot be implemented properly, regardless of whether the VFD is
running, the exception is not necessarily caused by interference. You can find out the causes
as follows:
1. Check whether the 485 communication bus is disconnected or in poor contact.
2. Check whether the two ends of line A or B are connected reversely.
3. Check whether the communication protocol (such as the baud rate, data bits, and check bit)
of the VFD is consistent with that of the upper computer.
If you are sure that communication exceptions are caused by interference, you can resolve the
problem through the following measures:
1. Simple inspection.
2. Arrange the communication cables and motor cables in different cable trays.
3. In multi-VFD application scenarios, adopt the chrysanthemum connection mode to
connect the
anti-interference capability.
4. In multi-VFD application scenarios, check and ensure that the driving capacity of the
master is sufficient.
5. In the connection of multiple VFDs, you need to configure one 120 Ω terminal resistor on
each end.
Solution
1. Check and ensure that the ground wire of the motor is connected to the PE terminal of the
VFD (if the ground wire of the motor has been connected to the ground block, you need to
communication cables between VFDs,
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Troubleshooting
which can improve the