Problem with frequency regulators sinamics v20 on modbus rtu communication

Hello gays,

I have a problem with frequency regulators sinamics v20 on modbus rtu communication. In addition to them, I have the sensors of the manufacturer regeltechnik, belimo valves actuators and samsung dvm heat pump. I have not yet got Belimo's actuators in communication, and with all other devices, PLC is communicating. The problem occurs when I start one of the frequency regulators. After that, I am no longer able to start any more, nor to switch off the already included frequency regulator, while, for example, the heat pump can be operated while the frequency converter is on. The frequency converter is switched off automatically when error F72 appears. All other frequency regulators also appear in this error at the same time.

I tried to disconnect the heat pump from the communication and then test it again and got a somewhat better situation in the sense that I can run other frequency controllers and stop them, but the response time is very long, even over 10, 15 minutes. After that, I disconnected all the communication devices except frequency controllers, and in that case they worked well.

I have 11 components connected to Modbus RTU network and they are not sorted by addresses, from at least to the largest, but randomly. PLC is Wago pfc200.

I someone had the same or similar problem, please send me some advises.

Thank you in advance!

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Split from V20 no speed from modbus (receiving but not running).

This is interference from the motor side of the installation; the inverter PWM output has an element of very high frequency imposed upon it due to the switching. This frequency, in the region of Mhz, will be leaking, capacitively form the motor and the attached cable, this leakage must get back to the 'noise' generator which is producing it, the V20 in this case. These leakage currents will be flowing though the communication cables, and anything which produces a connection back to the V20, and due to the high frequency, the connection will be both inductive and capacitive.

The solution here is to pay close attention to the screen of the cable between the motor and the V20, this must be continuous for high frequencies. Green and yellow, or round PE cable will not provide the right connection between these components, the impedance will be too high, only flat braid, or cable screen will provide the necessary low impedance connection between the motor and V20. 

High frequency leakage must be provided with a 'low impedance' connection between these components, unbroken by isolators and 'pigtail' connections. Failure to provide this path will divert these currents to your communication cables, to make the telegram unreadable.

Gland the screened motor cable at the motor, terminate the screen cable 'at' the V20. Try this with one V20, in order to prove the point.

Good luck with this, come back if I can help further.

Hi, I had the same problem with SINAMIC V20 and my problem was solved. Thanks a lot . I think it has a good manual to fix the problem .

https://support.industry.siemens.com/cs/attachments/109773836/V20_op_instr_1019_en-US.pdf?download=true