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.

[jgyates]

If the RBus comms are between the ATS and controller, I don't know how useful the would be unless the ATS is collecting a lot of data about the utility and generator output.

Does your capture indicate if there is a modbus master and if so is the ATS or the controller the initiator (master)? Genmon is the initiator (master) when communicating to other controllers.

If you want to attach it to this thread or send it to [email protected] I can take a look.

[bseishen]

RDC2, the ATS, and the Load Shed module are all on the RBUS. Guess is the RDC2 is doing the polling to the other 2 modules.

ATS is on ID 2. Load Shed Module is ID 1. ATS has voltage and current shunts in this system.
Found an old copy of kohler's diag tool. Was able to probe all of it's settings via the RDC2's usb connection. It exports an excel with all configuration information. I have removed my genset serial number from the data. If I was a betting man, I would expect the register structure would look very similar to the parameters tab on this sheet. Parameter 3304 looks interesting
3304 Modbus Is Modbus Master Write False

26RCA.xls
26RCA.txt

TXT file needs to be renamed back to an .sr file extension. This is the Pulseview file of the RBUS capture.

[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).