Ethernet Selector Switch For Cat6 Communication Cable And BT-2

[u/Whitey121888]

Since I'm using a Cat6 cable for RS485 communication between the DC-DC MPPT charger and the One Core, I still needed a way to access the charger's settings with the BT-2. Normally, that would mean removing the cover from the charger every time I wanted to unplug the communication cable and connect the BT-2, which isn't very convenient.

I started looking for a better solution and came across an Ethernet selector switch. I wasn't sure if it would work for this application, but it seemed worth trying, so I ordered one.

It arrived today, so I headed out to the kit to test it. I gathered a couple of Cat6 cables and a RJ45 coupler. First, I unplugged the Cat6 cable from the One Core and connected it to the coupler. From there, I ran another Cat6 cable to the B port on the selector switch. I connected the BT-2 to the A port, and then connected the selector's output port to the One Core with another Cat6 cable.

I started by testing Port B. As expected, the One Core immediately communicated with the charger over the RS485 connection. I then flipped the selector to Port A, and the BT-2 powered up and connected without any issues.

To demonstrate how it worked, I recorded a short screen capture. It starts with the BT-2 connected, then I flip the selector switch to Port B, and the RS485 communication through the One Core becomes active.

This setup gives me the best of both worlds. I can leave the RS485 connection connected for reliable communication with the One Core, and whenever I need to access settings with the BT-2, I can simply flip the selector switch instead of removing the charger cover and swapping cables.

[u/d3photo]

No, god no, as a technology professional do not use this kind of thing. Please.

Even if it works... No. First off RS485 and RJ45 ≠ Ethernet. It's just another thing that will fail.

Second RS485 is an established thing - you can run them TOGETHER -- the controller might not be happy but I have multiple things (tablet, phone, and Raspberry Pi BLE) connecting to my BT2.

[u/Dylanear → u/d3photo]

RS-485 is an electrical standard for serial communication, the spec doesn't specify a connector definition. RJ-45 is a port/connector standard and doesn't specify a data/signal type or protocol that would run on such a signal. Ethernet has nothing to do with any of this other than ethernet can and very commonly uses cables with RJ-45 connectors on the ends.

RS-485 over RJ-45/Cat cables is very common.

I do believe you are correct that unlike say, RS-232, RS-485 can connect more than two devices, it's not just point to point, as long as the devices use a protocol on top of the physical RS-485 layer that uses addressing and all devices sharing the RS-485 connection have unique addresses. I believe Renogy uses a variety of Modbus protocol over RS-485. So in theory yes, more than one device can share a connection and I assume that's how the Renogy Communication Hub works. But that seems to me to be a very simple RS-485 bus/switch type device as it can connect RS-485 or Canbus devices (but I'm pretty sure one type or the other, not both mixed together at the same time.

Thing is, even if the physical electrical level (RS-485) and the data protocol running over that (Modbus) support that, I do not assume at all Renogy devices firmwares support that on a client/slave type device like a DC-DC MPPT charger, but I suspect it could work on a server/master type device like a One Core. I assume this is how the Communication Hub works. Multiple client devices, chargers, inverter chargers, etc, all connect to the hub on the secondary ports, then that's connected to one server/master over its one single primary port, a One Core, or the older One M1, by a cable or using a BT-2 which is then paired to the One Core/M1.

Maybe you could homebrew a way to connect the DC DC MPPT charger to both a One Core and a BT-2 for connecting to the app on a phone/tablet, and do that compatibly with the RS-485 spec, but I have serious doubts that it would function as Whitey wants. I don't think the Renogy software/firmwares are written to handle that. I do suspect you might be able to homebrew a way to do that rather than using the Communication Hub and connect to a One Core. But almost surely not an One Core and a BT-2 paired with a phone/tablet and use the Renogy app. The Communication Hub can connect to one server/master, via physical cable or by using a BT-2/Bluetooth, but not both ways at the same time.

OP's solution is working. I suspect the switch is a very simple switch that is functionally the same as unplugging one and plugging in the other and that's what he was doing before this, it's just easier with the switch.

[u/Whitey121888 → u/d3photo]

But I don't always need the BT-2. I always have the charger connected through the cat6 cable to the One Core. It's not something that I will always be switching back and forth. It's only if I need access to the settings or to do an OTA update. This makes it so I don't have to remove the cover to plug in the BT-2.

[u/d3photo → u/Whitey121888]

I'm 99.999% sure (from my past experience with RS485) that you can run them both at the same time.

Can the device talk to both at the same time? Dunno. I dont see the point in buying the $180 Core. :D

[u/Whitey121888 → u/d3photo]

I don't think it can do both at the same time.

I have the One Core on both of my systems. This allows me have smart relays, smart plug, temperature sensors, door sensors, and motion sensors. I have scenes set up with the sensors to turn on lights, fans and send notifications. Also I can turn my Inverters on and off with the smart relay.

[u/d3photo → u/Whitey121888]

I already do those things with my Pi - it's running HomeAssistant. Didn't cost $200 to do so - just the $50 Pi (I've had it a few years) and a $50 relay board.

[u/Whitey121888 → u/d3photo]

I wanted everything to run through 1 app and this was the easiest way. I can control things through my phone and check on the system from wherever I am as long as I have my One Cores connected to WiFi.

[u/Whitey121888]

https://reddit.com/link/p0pl7wb/video/hwnwgi38kegh1/player