question

behl avatar image
behl asked

EM24 and ET112 on same USB Dongle

I have a EM24 on the USB Dongle and it workes fine. Then i added a ET112 (and changed the Modbus ID of the EM24 from 1 to 2 as described in the manual).

Now no Meter is recognised. If i disconnect one meter (EM24 or ET112) the other one works fine. So both meters are OK (and the cable too).

What can i do?

Multiplus-IIem24rs485
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behl avatar image behl commented ·
If i disconnect the GND connection between EM24 and USB Dongle then both energy meters work fine!

So there is no problem with the Modbus addresses

But the question is: should i regular connect the GND between the energy meters and the USB Dongle?

My configuration:

EM24 ----7m cat7 cable ---- USB adapter ---- 8m cat7 cable ----ET112

No termination, two twisted cables for A and B, another cable for GND

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Rob Duthie avatar image Rob Duthie behl commented ·
Hi

Yes you should run a ground that is what i have done and all woks OK.

I just used cat5 cable for mine.

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marcopagano avatar image marcopagano Rob Duthie commented ·
Hello together,

I changed the modbus IDs via Carlo Gavazzi Software. The both ET340 and ET112 are connected via one USB cable. Both are recognized by the cerbo GX but sometimes the ET340 is lost in the VRM with its data.

After 5-10 seconds it shows the actual data and after 30 seconds or 2 minutes the ET340 is lost again and appears after 5-10 seconds.

I use the original victron USB dongle with an 5m cable and the both ETs are connected at the end of the 5m parallel.

Does anyone had the same issue?

Thanks in advance and br

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Jan Brož avatar image Jan Brož behl commented ·

EM24 ----7m cat7 cable ---- USB adapter ---- 8m cat7 cable ----ET112

this is not a good way to wire up RS485.

You need something like this:

EM24(120ohm) --- eth --- ET112 ---eth--- USB adapter.

make sure you put 120ohm resistor between A+ B- terminals at the last device (EM24).

All devices in the system should have common GND.

the devices should be daisy chained, running separate wires to the two meters and paralleling them at the usb is not a good practice and probably won't work over distance.


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2 Answers
Rob Duthie avatar image
Rob Duthie answered ·

Hi

You need to change the ID address using the the CaloGavzz software not the Venus software.

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behl avatar image behl commented ·

I changend the ID directly on the Energy Meter - as described in the Victron Energy Meter EM24 RS485 manual.

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Rob Duthie avatar image Rob Duthie behl commented ·
Need to force it using the Carlo Gavazzi software that is how i have done using 2x meters on one cable and it works.
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marcopagano avatar image marcopagano Rob Duthie commented ·

I changed the IDs in Carlo Gavazzi Software and the Meters are correctly recognized, but the ET340 gets sometimes lost without any reason :(

Is the cable maybe too long. I used the original 5m one without any extension. Only cut it to passtrough to the second meter.

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l81ker avatar image
l81ker answered ·

the GX device addressing is limited. You have two choices, simple = run two separate RS485 cables. or more complicated change the device modbus address, but set them as discussed above on the actual meter using the Gavazzi software. Install it on a laptop, plug the USB RS485 cable into the laptop, change the address of 1. You must temporarily disconnect the one meter while you programme the other. I found it here. Page is Norwegian but programme runs in English https://www.gavazzi.no/nedlasting/software/software-ucs/

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Related Resources

Additional resources still need to be added for this topic

Energy Meter Manual EM24 RS485

MultiPlus-II Product page 

MultiPlus-II Manual

Multiplus-II GX Online Manual

MultiPlus-II 230V Datasheet 

VE.Bus Error codes

Additional resources still need to be added for this topic