Hi there. Did you actually get the meter to respond in the end? I’ve bought a similar one and have spent most of the afternoon trying to get it to speak to me! The docs say slave 1, 2400, 8E1 but nada.
Cheers
Tim Robinson
Two things to look at:
- It’s not unknown for the two legs of the bus to be swapped.
- MBus and Modbus are different protocols, and they don’t talk to one another. I write that because this Topic discusses both.
Hi Rob
I’m certainly aware that Mbus and Modbus are different beasts. However, the device is clearly labelled as RS485 Modbus per the photos which are very much modbus indicators. I’ve tried swapping A and B to no effect. It’s all mysterious. Did you get a similar beast to talk to you ok?
CHeers
Tim
Hi Tim, yes its in use and is working well. As I said, my ID was 34, 9600 8N1. Offset1, length 28.
Read holding register (4x)
Is your a 4 wire or 2-wire, mine is a 4-wire and oddly it runs from 5V, I was dubious because RS485 would be 10-36V, but I didn’t try it as I didn’t want to let the magic smoke out. If it’s a 2-wire then it must be Mbus.
I used CAS Modbus scanner to discover the ID then went from there.
Best of luck
Paul
Yes, that is Modbus (RS485 is the serial protocol in use). What USB adapter is it connected to? These again vary and that might be the issue.
Do you have anything telling you what address the device is at data is at and what data is mapped to what address?
Hi Phil
Thanks for your reply and encouragement.
I’ve ordered a more expensive branded RS485-USB adapter. Let’s see if this gives a more hopeful outcome! The ebay vendor told me the meter could take power from 5 to 24V so I gave it 24v as that’s the PSU I had to hand.
Cheers
Tim
so having failed with two dongles and a long-distance discussion with the meter vendor in China, they confirmed that the meter I had has not got modbus software installed in it. (eyerolls!) so I bought a Kamstrup 603 with Modbus and 230v mains modules. Works a treat! What do they say…’buy cheap, buy twice?’ Only issue with the Kamstrup is I can’t get more energy granularity than 1kWh on the modbus registers. I need to spend some more time poking it but even so, it should be fine for the purpose.
BR
Tim
You can use Emoncms Power_to_kWh input process to convert the Power data to higher resolution kWh energy.
For anyone still looking at this thread, I’ve just managed to read data via modbus from the zpmeter. Here’s the emonhub interface: