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rainerb asked

ET340 grid meter – how to find out the connection parameters ?

Hi,

my system contains a ET340 grid meter that is connected to a Venus GX device via Victron RS485 to USB converter cable.

As I’ve done years ago, I tried to connect the ET340 directly to my notebook with the same converter cable. Unfortunately I do not know the connection parameters anymore (baud rate, start/stop bits etc) in order to connect the Gavazzi Universal Software Configuration tool to the ET340. I aborted the automatic search after over two hours.


Is there a way to find out the hardware connection settings in the GX device (baud rate etc) in a config file or so? The Remote console shows only the device instance and a few other details.


Thank you and best regards

Rainer


Energy Meter
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1 Answer
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raymiller answered ·

First, if the automated search fails you may have the wires reversed.

I've found some information RS485 ModBus:

https://www.gavazziautomation.com/nsc/hq/en/energy_power_analyzers

If you use this link and search for ET340DINAV2 will bring up all the documentation and also software zip file for a windows computer to be able to directly talk to the energy meter.

You will need a USB to RS485 adaptor which is readily available on the internet for a small fee. On my Windows computer, the adaptor showed up as Com5.




Modbus address 1 (default) (Victron Energy only 1or2)

9600 baud

N parity

1 stop bit

Cabling:

ET340 connect A - (pin 9) to A- RS485 computer usb adaptor

ET340 connect B+ (pin 8) to B+ RS485 computer usb adaptor

ET340 Pin 7 to Pin 9 to terminate the RS485 in 120ohm resistor fitted to the energy meter at the slave end (as per Carlo Gavazzi manual). On the Master end of the cable should also be terminated in 120-ohm resistor. (if in dought measure with an ohmmeter when not powered.) Victron Energy site omits the terminating resistor connection ET340 pin 7 to 9, but this is necessary to ensure the correct operation and the lowest error rate of the RS485 Modbus which is just basic transmission line theory.

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