Just a little help RS485 please
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Hi there,
I am now more or less successfully monitoring from the RS485 interface (inverter is slave, semonitor is master). There are a few things that really puzzle me.
- I am only getting old data, data from days ago... Does the inverter store some amount of unfetched data?
- the process is going very slowly, it takes about a minute to get the next message, in the meantime messages are sent but apparently no response from the inverter. I also get "RS485 master ack timeout" a lot.
It looks like everything is setup ok, otherwise I wouldn't receive any data at all I guess. First I was trying to get connect the RS485 cable to my server, which involves about 12 meters of UTP cable. So I thought that might be the problem. So now I connect a laptop next to the inverter, cable is only 1 m long and now I am having exactly the same issue.
I also swapped the RS485 interfaces (computer side), I have one with a USB interface and one with an RS232 interface. This appears to have no effect at all. One of them has the option to set a terminating resistance of 120 Ohms, which I did and that also does not make a difference.
The UTP cables I wired like: A+ on orange, B- on orange-white, all other wires to ground.
So I really don't have clue here, can someone help me here?
That sounds more or less normal. The inverter stores quite a bit of old data. I'm not sure how much but it is many days worth. Eventually it should catch up and start sending current data. The normal rate of sending data isn't very fast and it varies quite a bit depending on how many panels you have and how much they are producing. This isn't a real time interface so you are never going to see a fast response. I'm not sure the cause of the "RS485 master ack timeout" message, but if the data you re getting looks reasonable then it's probably not doing any harm.
Ah thanks very much! That gives me hope it will going to work some time. So it's normal it can take 30 seconds between any messages?
At the moment I am not getting any data though, just "filler" messages. Wonder what that's supposed to mean! Just restarted semonitor and now I am again getting messages with real data. Interesting.
If you say "it's not realtime", will it be possible to have data from e.g. the last 5 minutes or not even that?
Do you have experience using the modbus interface (last resort if this isn't going to work, I know I won't have optimizer data then...)?
A message every 30 seconds or so from each inverter is about what I usually see. I'm not sure how exactly they decide when to send a 0x0500 message which contains inverter data and some, but not all, optimizer data. Inverter data should be from within the last minute, but data for a given optimizer might be updated less often. Expecting to see everything updated every 5 minutes during daylight is reasonable. At night there are just periodic keepalive messages.
I haven't tried to do anything with the modbus interface.
Ok, sounds good, thanks!
BTW for real-time measurements I also connected a meter, at least that always works :-) They have a led that blinks every Wh which I have monitored and counted.