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P1 to RS485 converter instead of ET340

I have a smart grid meter with DSMR v5 so it transmit a p1 telegram every second. I'd like to use this data as grid meter in ESS. In my understanding this is even more accurate then an ET340 which has a refresh rate of 2 seconds.

I'm thinking of the following solution:

  • I found a p1 to RS485 converter P1MB - P1 to Modbus converter | Xemex
  • After converting I could use the Victron Zigbee <-> RS485 bridge to transmit over the air
  • Connect the other end of the Zigbee bridge to my Cerbo.

What do you guys think? Is this feasible?

ronbeton asked
pyrorider answered ·

1 Answer

ET340 RS485 to USB connection problems

Looking for some assistance on getting an ET340 working with a CCGX, CCGX is V1.74 does this support ET340 as menu looks to be different to what manuals indicate. I'm using 5M USB to RS485 Victron cable, no interference across installation, orange,yelow and black as instructed, CCGX does not see ET340 at all, plugged into USB host port on CCGX, no red or green flashing light (only on initial plugging in, then only get a solid red led (not the traffic led). Tried connecting ET340 to a Win 7 home PC with Carlo UCS7 software but that doesn't appear to work either. Have tried multiple USB ports, various USB to RS485 cables that I have on hand, linked in 120Ohm resistor on ET340. No luck at all, thinking I have something DOOB but thought I'd throw it out there for advice.

surefk asked
jetlag commented ·

3 Answers

Et112 loss of communication and warranty

Hello everyone

I am having some trouble with an et112 meter not communicating anymore with my octo gx, this has been working for 1 1/2 years but now is not sending data.

I have tried to connect it with a victron rs485 to usb adaptor no change and downloaded Carlo Gavazzi ucs7 and it will not find the unit so i am fairly certain it is faulty.

So i have contacted the supplier (on ebay purchase april 2021) and they said they would get their technical department to contact me and i have heard nothing.

as you can understand this is a crucial part of an ESS system and i would like to get this working as soon as possible what is the serial number that i need for a support request? (various numbers on box and unit but not starting with HQ)

Hopefully someone can help



zetecnology asked

0 Answers

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?

behl asked
l81ker answered ·

2 Answers

Is it possible to send data via RS 485 from a GX-device?

We would like to power a PCU ( from a battery pack that is monitored by a BMV712 and a Venus GX. The PCU needs information about state of charge off the battery and voltage. This can only be send to the PCU via RS 485. Is there a possibility to send information via RS485 from a Venus GX to the PCU? Or can we better change to a raspberry Pi with Venus OS installed?

leenderthameete asked

0 Answers

Possibility to change EM540 modbus driver to read consuption with higher resolution

I just found out, that the modbus RTU (RS485) driver for the EM540 energy meter in the current venus OS 3.00~14 is reading the register address 0x0034 (kWh (+) TOT) with the length of 4 bytes (INT32) as the total energy (Value weight: kWh*10). The resolution is 0.1kWh. This seems to be a small resolution for small households as for example the hourly consumption is around 0.2-0.3 kWh. So in the VRM portal the statistic is relative coarse...

My suggestion is not to read register 0x0034 but 0x5000 with 8 bytes length (INT64) as the total energy (Value weight: Wh) instead. This would give a resolution of 0.001kWh and would be much more accurate.

I got these information from the Carlo Gavazzi EM540 communication protocol PDF available from the internet. Could that change be implemented in future versions?

And as the duty cycle for the rs485 bus with 9600baud is quite high for the high speed update rate of the EM540, would it be a possibility to add a higher baud rate option? E.g. 57600 baud?

christiangurk asked
christiangurk edited ·

0 Answers

Connect Smart Meter to Cerbo GX

Hi, I must connect a smart meter “Chint DDSU666-D 80A 1Ph” to a CERBO Gx.

From smart meter come out 2 wires using RS485 protocol.

According the meter manual, I must connect this 2 wire to the pin 7 and 8 on the RJ45 connector.

I read the Cerbo Gx manual and in the wiring picture seems I must use the USB port, not the RJ45 port, but in the picture use Zigbee wireless to RS485 adapter and Zigbee wireless to USB, not direct by wire. it’s that true? What connector I must use?

What pins I must connect to the 2 wires?


kyuketsuki asked
kyuketsuki answered ·

2 Answers

ET 112 not showing up on Cerbo - 15m away


After hrs of going round in circles, using the RS-485 to Cat6 Extention to the USB - RS485 adapter still nothing... Any help would be appreciated.

sales-1 asked
jodi5d answered ·

1 Answer

Availability of Isolated USB - RS485 transceiver


Due to the global issue of chip stocks, the Victron recommended "Hjelmslund Electronics USB to RS485 Iso converter" hasn't been available for a while.

Can anyone recommend another Isolated RS485 transceiver for a Multiplus II 48V/10000, is anyone using a RS485 repeater ?

My ET112 modbus meter will be 50 metres away at the supply and baud rate will be 9600.

Best regards


simat asked
Juha Tuomala edited ·

6 Answers

ET112 to Cerbo 50 rs485

Hi. Is it possible to connect ET112 to Cerbo with 50 metre rs485 to usb cable

darrencham asked
Jay edited ·

5 Answers

trouble with ET340 connection by new Zigbee 485(DRF2659c), USB (DRF2658c) module

Hi there,

please, let me ask for help if possible with the new zigbee RS485 (DRF2659C) and USB(DRF2658C) module that I would like to use for wireless connection of ET340 to Venus OS.

I have trouble with them to be recognized be Venus OS (2.73 and 2.80). I find out that zigbee modules come with quite new firmware v8.5 and it has ID_MODEL=USB_Serial, that I have adjusted in "serial-starter.rules", in "" and I have played around also with serial-starter.conf. Without success till now.

When I do wired connection all works well and ET340 is recognized as device ID:345 with 2571291A number and is visible by Venus OS . See screenshot 1.

When I set it with zigbee, there is no info about find cgwacs device. See screenshot 2.

Any suggestion what I could try is welcome? Thank you.

Best Regards,


1. Wired connection


2. Zigbee connection


3. USB-zigbee module


hsaman asked
dimiwa commented ·

3 Answers

VenusOS, Modbus and compatible devices (Heatpump Ecodesign ED 180RF)

Hello everyone,

I am an enthusiastic VenusOS user managing 2x systems based on it. Currently the systems are fairly straightforward with solar panels, Lifepo4 batteries, MPPTs, and inverters.

Now I find myself in the need to add a heat pump (Ecodesign ED 180 RF) for hot water production and I was wondering about compatibility/interfaceability.

The manufacturer tells me it has Modbus interface and that it is compatible with all systems supporting this bus. In this case, the interface would allow to readout values and set thresholds.

My question is whether anyone knows if this is supported by VenusOS (via RS485-USB converter). Or actually whether in general hot water generating systems are supported and can be monitored within VenusOS. Off course, if this would be even accessible within Node-RED this would be the cherry on top ;-)

Thank you in advance for your inputs!


dgnoise asked
dgnoise answered ·

2 Answers

connection between Si-RS485 and CCGX


Trying to connect a Ingenieur buro Si-RS485 to VRM. Setting:

Si-RS485 ---- > 12V from 24 to 12V transformer and RS485 to USB cable 5m (VE bus Multiplus V 430) -------> USB 12m self regenerating -------> CCGX (V 2.91) -------> Modemrouter -----> 3 and 4G ----> Internet ----> VRM


No answer from VRM,

Impossible to use Modbus setting from a PC attached on same network


Not a specialist, just a self trained Victron's user


Any tip???


Lionel SEYDOUX asked

0 Answers

EM24 Rs485 vs. Ethernet

I‘ve heard that an ESS system with an EM24 RS485 is much slower in comparison with an EM24 Ethernet. I‘ve been told that the RS485 variant needs up to ten times longer for measuring and therefore the complete regulation of the system is quite slow. Is that right?

Henning Schewe asked
hardy-tuner answered ·

1 Answer

Energy Meter ET112 communication link

Like many before I have been challenged by installing an ET112 "grid meter" at mains AC entry point when my whole solar setup is in an outbuilding around 40m away. Hard wired communication back to a Multiplus 2 GX is just way too complicated, and would require laying underground conduit to hide cable runs across a large parking area. I did consider the Zigbee option, however, from my experience of trying to get a decent extended WiFi signal to my outbuilding I am not even sure the Zigbee would guarantee a solid connection (it is effectively a wireless mesh system operating on the same 2.4GHz as WiFi. At that frequency passing through 3x 25cm solid walls over the distance required is probably on the edge of operation?).

My thoughts turned to a RS485 radio link. At this stage I know I am subject to scrutiny and I make no guarantees that this would suit everybody's situation. If I could I would go for a hard-wired link... but I can't. I absolve myself from all liability if anyone decides to copy my project.

I have done some projects with LoRa in the UK so the available 868MHz band is well known to me. I stumbled across a RS485 transceiver board on ebay (....don't you just love it?), made by our friends in a different time zone. So, I purchased 2 of these boards to play around with. They use FSK modulation and make the board in 433/868 MHz versions (check your country rules!!). Ideally they run on 5v and the manufacturers claim a free air (line of sight) range of 500m. They appear to do what they claim.

The next part of the puzzle is the link to the GX device. Victron "recommend" FTDI UART chip based serial communication by implication (....that is what their standard connection cables seem to be based on?). There are 2 other UART chip devices in general circulation the CH340 and the CP2102(SiliconLabs). From what I have found the Victron equipment does not natively communicate with CH340 devices (you need the drivers installed). The CP2102 chip works with a Venus GX I have on a raspberry pi system and also with Multi 2 GX (which effectively has a Venus inside). I have not tested with Cerbo GX but there is no reason to assume it will be different since the software is all Linux based?

The USB to RS485 device I bought was the DSD Tech SH-U10. Which is a dongle that plugs into my raspberry pi. Be aware that this will not fit within the Multiplus 2 removeable protection panel over cable entry. You could just get a USB extender cable so that the dongle is outside or, as I am going to do, buy the DSD Tech SH-U10L which comes as a connection dongle on the end of a USB cable... much neater solution.

The transceiver uses less than 30mA at 5V so at the Victron end mine is powered off the DSD SH-U10. However, I have built small mains powered 5V DC power supplies into my devices so that I can run the radio link off a fused spur at my consumer unit end. In fact I used the opportunity at the grid entry point to install a Mains isolator between electricity board meter and house consumer unit in a small secondary consumer unit (designed for garages/outhouses etc). That also neatly houses the ET112 meter, since there was no space left in the main consumer unit.

So, that's it. I 3D printed some ABS boxes for neatness and to keep it housed safely. Although I only "need" the power supply at one end I have just printed the same box at both ends. I have played around with different cable options and have decided that standard internal BT telephone cable is a good option, it is just 2x twisted-pairs within the same cable. Of course this has not been tested to extreme but it has been soak tested for a week or so and appears to connect flawlessly?



gazza asked
gazza edited ·

0 Answers


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