Is it possible to monitor control module via modbus RS485

[ACordero07]

I want to monitor my generator using a USB-RS485 adapter module, could someone help me?

[jgyates]

The RS-485 traffic on the J6 connector is not related to modbus. It uses another protocol. This interface is used by the controller as a separate method of communication that supports Generac mobile link. This project does not support this communication link.

I assume it is possible if you reverse engineer the comms, but I have not done that as this project predates the Evolution 2 controller and being modbus based, this project can easily support other generators besides Generac.

[ACordero07]

I try to perform the following test, and with the Modscan software I plan to read the information

I have one more, in the link you shared with me I found this
"0007": [2, 0], # Engine RPM (Nexus, EvoAC, EvoLC)
but I would like to know what the ID address would be, I would like to think that:
0007: refers to the Modbus register for RPM
what is in [2, 0], I don't know what it refers

[jgyates]

The Evolution controller uses modbus address 9d hex. Other models like the H-100, Deep Sea, and Kohler the modbus address is a setting in the controller.

Regarding the [2,0], the 2 is the size in bytes (modbus minumum read is 2 bytes) the zero denotes a flag internal to genmon (used for debugging) and has no significance for the modbus protocol.

[jgyates]

a few comments / questions.

1. you wiring diagram does not show a ground connection. This is required with RS-232. you must have the controller and your RS-232 interface on a common ground.
2. I don't know what software you are using to communicate with the controller so I can't help in that area. The picture above showing Communication Traffic would need explaining.
3. If you are wanting help on communicating with you controller via mobus an do not want to use genmon, then it would probably be helpful to describe what you are tying do do to put you actions in context. Using third party software only complicates the situation if your goal is to use genmon
4. What is the significance of the traffic in the diagram above showing traffic 9d 03 00 03 00 0a 28 51? Are you trying to read modbus registers with third party software? This reads 10 registers (20 bytes) starting at address 0003. I would only read one registers at a time and not registers 3 as that is not a readable registers on Evolution. Read registers one: 9d 03 00 01 00 01 xx xx. You can read multiple registers but the device can also chose to to support that and not all registers have to be readable. Some controllers respon with exception packets if you try to read an unsupported registers, others just ignore the request.

[jgyates]

Post a picture of your RS-232 cabeling. Sometimes there is confusions with the orientation of the molex connector. Sometimes swapping the TX and RX helps as some serial adapters are labeled as a DTE vs DCE (i.e. what the pin is vs what it should be connected to).

The Evolution 2.0 does not export oil pressure over modbus.

This sequence should read the RPM:

   9d 03 00 07 01 xx xx

I would suggest asking the makers of Modbus Poll if there is anything you can do to debug this as I have never used that software. Outside of giving the register info and checking your cabeling I would not know what to suggest.

[jgyates]

I do not have any documentation or signal map for the Evolution controller. I would suggest converting the numbers to hexadecimal and searching the address in this source file:

https://github.com/jgyates/genmon/blob/master/genmonlib/generac_evolution.py

If you convert 1517 to hex that gives you 5ed. If you search "5ed" or "05ed" in the link above you will find all of the occurrences of the ambient temperature. Note that this file supports multiple variants of the generac residential generator (air cooled and liquid cooled Nexus, Evolution and Evolution 2.0, Power Pact, etc) with each variants being a little different so not all modbus registers will apply to all variants.