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arvid avatar image
arvid asked

Victron USB RS485 converter to connect EM530 to PC

I have installed energy meter Carlo Gavazzi EM530 and installed the program UCS-7 (Carlo Gavazzi) on my PC for presentation of measurement data. I want to see the data from the energy meter on my PC before I connect the EM 530 to the Cerbo GX. I have used a 15 m RS485 cable from the meter to the Victron USB RS485 converter which connects to my PC.

The connection has been checked several times

Problem: I have no contact with the meter when I use ModbusRTU and search for the energy meter from USC-7.

The Victron USB RS485 converter only shows a constant red light and no RX or TX signals.

What is wrong?

rs485
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2 Answers
Duivert NL avatar image
Duivert NL answered ·

Did you power the meter L1 and N?

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arvid avatar image arvid commented ·
Power meter EM530 is internally powered, I use EM530 in a 3 phase-3 wiresystem which is common in Norway.
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arvid avatar image arvid commented ·

EM530 works OK at the installation place close to the distribution board

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Duivert NL avatar image Duivert NL arvid commented ·

Yes ok, but is it powered?

as far as i know and have experience with different cg meters is that they need power to communicate with the software, they are not powered from modbus/rs485

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arvid avatar image arvid Duivert NL commented ·

Thanks for answear but on the EM530 there is no way to put more power. I have conected the rs 485 cable to B+, A- and Ground on EM530 according to the installing manual

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Duivert NL avatar image Duivert NL arvid commented ·

so the meter is connected to grid?

does the ucs7 software connect with your usb/rs485 interface? (COM),

because the lights on the usb converter should flash even if there is no connection to the meter!



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arvid avatar image arvid arvid commented ·

I have tried to measure voltage between B+,A- and Ground and I measure no voltage either AC or DC.

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Duivert NL avatar image Duivert NL arvid commented ·

you cant really measure rs 485, its a digital 5v dc signal, check if your software/pc communicates with the usb converter first, looks like thats the problem, could also be a faulty converter

just tested on of mine (original victron) and it flashes with ucs software without meter connected ...

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arvid avatar image arvid Duivert NL commented ·

I have now connected my victron usb-rs485 converter without load to my PC. It is connected to Com 4 and gives a constant red light, no flashing

When I look at the Device Manager in Windows 11 it says: This device is working properly.

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arvid avatar image
arvid answered ·

I got a new Victron USB RS485 converter which was connected to the Cerbo GX after the 1.8 m long cable was shortened to 10 cm. Correct end termination both on the EM530 and on the Cerbo GX.
Still no connection. When I replaced the Victron USB RS485 converter with the USB RS485 converter DFRobot Module FIT0737, everything was OK without having done termination with a 120 ohm resistor on the Cerbo GX side
Problem solved, but I don't understand why Victron's own USB RS485 converter doesn't work

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