Triron 4210N and multiple RS485 devices: NOOB /sorry

Can I daisy chain multiple rs485 devices to my EPEVER Triron MPPT? I want to use the MT50 display and RS485/USB PC software at the same time.

The MT50 display is rs485 with an RJ45 plug on it
There is an RS485 usb cable for PC software with an RJ45 plug on it
The Triron 4210N has an RJ45 port marked "RS485 Slave" for these items to plug into, but only *1 port.

I am assuming the port is for the slave and the MPPT is the actual master?
I understand that 485 is 2 wire serial and and far as I can tell RS485 can simply be parallel daisy chained with the master handles polling the slaves.

I have been trying my keister off to find the answer on my own, and I just don't know enough to figure it out. PFA Thanks!
 

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Hedges

I See Electromagnetic Fields!
The stuff I use (SMA) has multiple RS-485 slaves. Master happens to have an RJ-45 plug and they provide a wire with 3 terminals data+, data-, gnd.
The slaves have screw terminals, and I stuff two wires into each except for last slave, where the last wire terminates.
Master and last slave each have a parallel termination resistor. That is enabled with a shorting plug on a header for the slave. Master has RJ-45 in and out jacks (in case it is in the middle), and an RJ-45 plug with terminating resistor goes there.
Somewhere in the daisy chain, a pullup for data+ and pulldown for data- is required. Slave has that as well, with header for shorting plugs.

Not sure which of your boxes is master vs. slave but expect monitor to be master. RS-485 is relatively slow (mine runs very slow at 1200 baud) so short stub is OK. If you use a short cable with RJ-45 on one end, you could connect its wires to the wires daisy-chaining between equipment.

But your USB/software interface probably also wants to be master. There are some obscure multiple mater schemes; wouldn't expect that to be reliable or multi-manufacturer. You're probably better off switching between them.

My system somehow does multi-master. I haven't figured it out. My monitor can plug into the bus and use it, while my battery inverter communicates on/off grid operation over the same bus. I've captured the monitor's communication with a scope, but never saw the battery inverter's signal.
 

labeeman

Solar Enthusiast
Can I daisy chain multiple rs485 devices to my EPEVER Triron MPPT? I want to use the MT50 display and RS485/USB PC software at the same time.

The MT50 display is rs485 with an RJ45 plug on it
There is an RS485 usb cable for PC software with an RJ45 plug on it
The Triron 4210N has an RJ45 port marked "RS485 Slave" for these items to plug into, but only *1 port.

I am assuming the port is for the slave and the MPPT is the actual master?
I understand that 485 is 2 wire serial and and far as I can tell RS485 can simply be parallel daisy chained with the master handles polling the slaves.

I have been trying my keister off to find the answer on my own, and I just don't know enough to figure it out. PFA Thanks!
If you can set the address of the slaves you can have more than one device on the RS485 up to 32 devices most of the stuff I have seen coming out of Asia for solar you cannot set the salve. You can only have one master.
 

NPhil

Freezing in the dark non-enthusiast
Customer service says I can do it if I use a 1m2s adapter.

I think I can do it much more simply.... I'mma find out!
I have a similar situation, I received an MT-50 today, and I have been using the RS-485 to USB connection to monitor the unit. I expected to plug them both into provided ports, but, no. So, I found this, refreshed my recollection of RS-485, searched Amazon, and found this, which I think will work:

 
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Symbioquine

Solar Enthusiast
As other folks have indicated, there can only be one master making requests via RS485/Modbus (RS485 refers to the mechanism by which the signal goes over the wires and Modbus refers to the protocol) at any one time.

Modbus is a request/response protocol where the master always initiates each exchange. It does this over RS485 by setting the A and B pins of the RS485 connection to high or low voltage values to communicate the bits of its request. If two masters tried to send requests at the same time, they would combine to create a nonsense signal that no slave would be able to respond to. Similarly, a slave sets those same A and B pins voltage values to respond - so if a second master tries to make a new request while a slave is sending a response, the response will become corrupted.

Fortunately, Modbus requests/responses include a checksum - data included in each message to help validate that the payload of the message matches what was intended to be sent. This means that the most likely failure mode is requests/responses which are seen as corrupted and discarded. Depending on the systems involved, this might impact every request or only a rare request here and there.

I expected to plug them both in to provided ports, but, no. So, I found this, refreshed my recollection of RS-485, searched Amazon, and found this, which I think will work:

https://www.amazon.com/gp/product/B07CW7JHYV/

That would physically work, but will result in corrupted/discarded messages. Don't do it this way if you want your system to work reliably.

Customer service says I can do it if I use a 1m2s adapter.

Yes, I believe this device works by acting as a master itself when talking to the SCC (Epever Triron), then in turn acting like a slave when talking to each of the other masters. It receives requests from each master and proxies them to the SCC - making sure that only one request is active at a time to the SCC. None of the requests collide or get corrupted because there are three separate RS485/Modbus connections - one each from the masters to the 1m2s adapter and one from the 1m2s adapter to the slave(s).

If you don't want to buy the 1m2s adapter you could implement your own system to proxy requests from one or more masters.

I did this for a while using a Raspberry Pi so I could have the MT-50 connected while still gathering metrics with my custom code on the Raspberry Pi. The setup is roughly described in the first part of [this blog post](https://symbioquine.net/2020-10-27-epever-esp-8266-controller) and the code was something like what I've linked to in https://diysolarforum.com/threads/s...ever-controller-with-python.25406/post-300209

1631284241073.png

https://gist.github.com/symbioquine/00b3884b2d41ce69edb3547112706289
 

Hedges

I See Electromagnetic Fields!
As other folks have indicated, there can only be one master making requests via RS485/Modbus (RS485 refers to the mechanism by which the signal goes over the wires and Modbus refers to the protocol) at any one time.

I'm still trying to figure out how SMA accomplished multi-master on RS485.

Sunny Island uses RS485 to signal Sunny Boys whether it is on-grid or off-grid, and they switch their parameters accordingly.
Sunny Data Control or Sunny WebBox can ride on the same RS485 and get/set Sunny Boy parameters & data. WebBox is able to do that with Sunny Island parameters as well.

I've been able to capture RS485 traffic from Sunny Data Control with a scope. I've never triggered on & captured Sunny Island's traffic. But I've observed Sunny Boy's response to Sunny Island, switching between on-grid and grid-backup modes.
 

Symbioquine

Solar Enthusiast
I'm still trying to figure out how SMA accomplished multi-master on RS485.

Sunny Island uses RS485 to signal Sunny Boys whether it is on-grid or off-grid, and they switch their parameters accordingly.
Sunny Data Control or Sunny WebBox can ride on the same RS485 and get/set Sunny Boy parameters & data. WebBox is able to do that with Sunny Island parameters as well.

I've been able to capture RS485 traffic from Sunny Data Control with a scope. I've never triggered on & captured Sunny Island's traffic. But I've observed Sunny Boy's response to Sunny Island, switching between on-grid and grid-backup modes.

I don't know anything about SMA or Sunny Island/Boy.

That said, it's possible to have multiple masters playing nicely on a single RS485 connection if they're designed to coordinate with eachother. Modbus is an extensible protocol which intentionally leaves some space for "vendor specific" commands. In theory one could implement a protocol on top of modbus where the "masters" coordinate which one is supposed to be sending/receiving commands - kind of like passing a talking stick at a meeting. I thought about mentioning this on my previous response, but it wasn't relevant to OP's question since the MT-50 doesn't support this AFAIK. :)
 

NPhil

Freezing in the dark non-enthusiast
I have two, eh, reasons to go ahead with my plan.

1. I really want to buy those splitters, because the comments are so entertaining that I am tempted to add to them.
2. I wonder what will happen if I plug everything together (because the refreshing of my understanding has come as far as knowing that RS-485 allows multiple transmitters, where RS-422 doesn't), and, if it doesn't work, send an email to support and ask why not?
 

Symbioquine

Solar Enthusiast
I wonder what will happen if I plug everything together (because the refreshing of my understanding has come as far as knowing that RS-485 allows multiple transmitters, where RS-422 doesn't)

It will probably work at least some of the time. My experience with the MT-50 suggests that it will occasionally flash "Connecting..." on the screen when its requests get interrupted/corrupted.

if it doesn't work, send an email to support and ask why not?

I'll be curious to hear what they say, but I suspect that customer support will just tell you the same thing I am and that it's not a supported configuration.
 

NPhil

Freezing in the dark non-enthusiast
It will probably work at least some of the time. My experience with the MT-50 suggests that it will occasionally flash "Connecting..." on the screen when its requests get interrupted/corrupted.



I'll be curious to hear what they say, but I suspect that customer support will just tell you the same thing I am and that it's not a supported configuration.
I received the connectors a couple of days ago. The MT-50 began flashing "Connecting...", as soon as I paralleled the connection to the laptop. I didn't wait a long time, but it didn't seem as if it was about to stop. BTW, what I received when I ordered two of the two packs from that link in my comment above was a total of 4: two "couplers", type "A/B" and two "couplers", type "Cat/5A/6A"). The type "A/B" are useless for tying RS-485 devices together on a bus, but the type "Cat/5A/6A" will (physically connect devices, they still have to be programmed to interact, which my MT-50, RS-485 to USB adapter, and the RS-485 connection on the Tracer evidently are not) connect them. A pair of type "A/B" will, I just tested it) merge two physical Ethernet connections (if they don't require the 2nd 2 pairs of Cat5) to share one cable. That's actually something I might need. The other ones, I don't know. Maybe. If I recall correctly, this is the first time I ever connected three RS-485 devices.
 
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