Any work done to reverse the RDC2 for Kohler residential gensets?

[bseishen]

Looks like the comms between the RDC2 controller and the RXT transfer switch is Modbus. Wondering if anyone has any prior work looking at the signaling between the two. Love to get higher sampling rates and get away from the oncue API.

[jgyates]

I have not looked at the RCD2 controller in any way. I don't have any documents that describe the modbus registers. Typically to add a new controller the 4 steps listed here are followed:

https://github.com/jgyates/genmon/wiki/Appendix-N-Genmon-Supporting-Other-Controller-Types#the-process-of-creating-a-new-controller-support-within-genmon

I would peform step 3 if given the data from steps 1 and 2.

[bseishen]

Unfortunately at first glance, it looks to be a bastardized version of modbus named "RBus" I do have a sigroc capture of the modules communication. 1/2 of the packets do adhere to Modbus RTU standards, others are missing or adding additional bytes. Com speed is 19200 8N1.

RBUS (PROTOCOL)
Rbus is a KOHLER proprietary protocol developed
primarily for use with residential and light
commercial products. It communicates over the
RS-485 hardware layer and creates a holistic
solution among KOHLER generators, transfer
switches, programmable interface modules, load
control modules and similar devices. Because it is
proprietary, it does not allow communication with
nonproprietary systems.

[arw00d]

This is the block on the generator and this is mirrored on the ATS

[jgyates]

I would guess this is RS-485 (A and B connections) with a power (PWR) and ground (COM). Not sure what 3 and 4 are. This page has some info on RS-485 connecting to other generators that are used on this project. You can use a pi HAT or a serial over IP converter (links on the page referenced).

[arw00d]

Sorry to be dense, but would I need those things in order to read anything coming off those terminals or could I just probe A and B with my signal analyzer and get a reading? This is what I was hoping bseishen could help clarify, i.e., how he got the data he shared above.

[jgyates]

you probably could get the data from your signal analyzer. This assumes the analyzer would interpret the data rate, start and stop bits in the serial.

[arw00d]

Makes sense. I think that is all stuff I can adjust once I have a capture. Much like with Pulseview. I'll see if I can get time to explore some of this this week...

[k5map]

@bseishen ... is your Kohler connected via Ethernet or WiFi? I have a 26kW Kohler being installed next week and plan to connect it via Ethernet with the hopes of getting genmon to connect to it over TCP/IP

[bseishen]

Over Ethernet. I pipe it into home assistant with the built in plugin. Grid down situation usually is when the internet drops. I'm assuming the TCP/IP side will be a harder nut to crack. Would have to redirect devices.kohler.com to a local service spoofing kohler's server.

[k5map]

I'm not so much interested in intercepting the comms from the generator to devices.kohler.com as much as finding a way for genmon to communicate with it on the same Ethernet interface so we can have both options; Kohler app (for my wife who doesn't care about all of the technical data) and genmon (solely for me).

[k5map]

@bseishen ... any update on getting genmon to work with your Kohler RDC2 controller?

[bseishen]

I was trying to track down my RS485 adapter, but I'll order another one. There might be another rs485 port on the RDC2 too.

[k5map]

The service department of my dealer has been very helpful, so I've asked them if they know of a RS485 connection on the RDC2. If so, where is its location. I'll let you know if I get a positive response.

[silverfun9989]

I am also starting down this journey, I have the DC2 controller (less buttons) but I will drop a network tap in between generator and switch to see what that has and also see if I can tap the rs-485 bus on terminals a,b,com and power.