Suddenly no connection between Cerbo GX and EM24 USB

DIY
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1

Hello

the entire system ran for around 2 years without any problems, with a MultiPlus II, 10 kWh battery, a Cerbo GX and the EM24 USB.

For the past 3 days, the EM24 has no longer been listed in the Cerbo. "No grid meter warning’ cleared on 'Gateway [0] "

All 3 LEDs on the USB connector stay lit continuously. Nothing is found when scanning for Modbus devices.

I disconnected the cable from the EM24 and measured a voltage. The cable has 0.15 V and 0.5 V on it. The EM24 has 2.5 V at both terminals.

Can anyone give me a tip as to where the problem lies?

Many thanks,
Christian

2

Have you tried resetting Cerbo and meter?

3

Yes and no, I’ve restarted both devices and also completely disconnected them from the power supply. Is that sufficient?

4

Should be enough, it may be an error on the USB cable, you may try plugging it on the other USB of the GX l, if it’s a Cerbo or a Ekrano

5

You have an EM24 with RS485, and then you’re using an RS485<->USB converter, right?

If so, some of these converters have earthing issues. It would be very important here to use isolated or galvanically isolated converters. The original converters from Victron can do this, as can products from Waveshare, for example.

You could also try connecting the USB cable to the laptop and reading it using the Carlo Gavazzi software. If that works, then at least the EM24 and the cable are working properly. The converter connected to the Cerbo could still be the problem if it has a voltage offset, or of course it could be the Cerbo itself.

Did you plug it directly into the Cerbo or via a USB hub? Try a different USB port, and if you’re using a hub, try it without the hub or try a different one.

6

Thanks,

regarding Juan’s reply,

I’ve done that, but the second USB port made no difference either.

Regarding Jetlag’s reply,

that’s right, I have an EM24 with RS-485 to USB!

I have the same problem on the laptop with the Carlo Gavazzi software: no communication (no COM port detected); all three LEDs are lit, but not flashing.

Is there any way I can narrow down whether the cable or the EM24 is likely to be the problem?

7

You could try replacing the RS485-to-USB converter; it costs less than €20.

Before that, you can also check whether the cable between the meter and the USB adapter is OK, i.e. whether it has continuity.

The EM24 has a rotary switch; this switch must not be set to the padlock position.

8

Hello,

For me, the cable and the RS485-to-USB adapter are a single cable (Victron).

I’m ordering an RS485-to-USB adapter, and then I’ll be able to continue using a standard data cable.

The switch isn’t set to the padlock symbol.

I’m curious to see how it goes, but I’ll have to wait a few days now.

9

Oh right, but then you already have the original Victron interface converter, which is galvanically isolated. So that shouldn’t be the issue.

Now try it with the replacement converter; maybe it’ll work then… Otherwise, as I said, test it on a PC, or in the worst case, the EM24 itself may be faulty.

Do you have a terminating resistor connected?

It might help…

10

The new interface converter has arrived and — no luck — what a shame!

There are two termination resistors connected to the Cerbo — are these the ones being referred to?

If I buy a new EM24, would it be better/more stable to use an IP-based one?

11

Have you also tested it on a PC?

I mean, did you connect the new converter directly to the EM24 instead of the old one, and then try it on a PC using the Gavazzi software?

By termination resistor, I mean the one on the RS485 bus, i.e. directly on the data lines at the EM24.

If you’re planning to replace the meter, go for the newer EM540, which also uses RS485. You already have the converter and the wiring. It’s newer and a little faster.

12

Today was the day—the EM540 arrived. I dropped everything, switched off the power to the entire house and installed it. That’s it, everything is working again—we’ll be running off the battery again tonight.

Many thanks to Jetlag! (-: And I’m thrilled by how much faster the EM540 is, so many thanks for that too.

What isn’t working yet is Home Assistant—it can’t see the EM540, but that’s a separate issue!

13

In that case, it was probably a faulty meter after all… Perhaps it was hit by a power surge at some point?!

Have you installed a surge protective device (SPD)?