| Re: [volttron-dev] [EXTERNAL] Re: Custom Controller Agent Causes Modbus Read Error |
On February 23, 2024 at 11:42 AM EST volttron-dev@xxxxxxxxxxx wrote:Hi Bora,
Thanks for the response. Unfortunately, I do not really follow your point or know what I should do with this information. I have these 2 devices configured under the platform.driver like this:
Is this what you mean by “multiplex the controls through the platform driver”?
-- Joe
From: Bora Akyol <fstshrk@xxxxxxxxx>
Date: Thursday, February 22, 2024 at 6:20 PM
To: volttron developer discussions <volttron-dev@xxxxxxxxxxx>
Cc: "Thompson, Joe" <jthompson@xxxxxxxx>
Subject: [EXTERNAL] Re: [volttron-dev] Custom Controller Agent Causes Modbus Read Error
Your modbus devices do not support multiple modbus primaries. You need to multiplex the controls through the platform driver. There is no reason to have two modbus primaries On Thu, Feb 22, 2024, 12: 25 PM Thompson, Joe via volttron-dev <volttron-dev@ eclipse. org>
Your modbus devices do not support multiple modbus primaries.
You need to multiplex the controls through the platform driver. There is no reason to have two modbus primaries
On Thu, Feb 22, 2024, 12:25 PM Thompson, Joe via volttron-dev <volttron-dev@xxxxxxxxxxx> wrote:
Hello Volttron Team,
Background:
I am using Volttron 8.1.3 on a Raspberry Pi to coordinate the operation / testing of 2 devices over Modbus:
- An energy storage system with a BMS that Volttron’s platform.driver communicates with over modbus
- An inverter that also communicates with Volttron’s platform.driver via modbus
Using the Listener Agent I can see that the platform.driver is reading all of my modbus points perfectly every 5 seconds (see the attached volttron_Without_Controller.log).
I have a simple custom agent, enervenue_ctrlagent (see the “agent.txt” file, changed from “agent.py” for attaching), that is subscribed to the "devices/STAC/EnervenueBMS" topic and runs a simple read from the battery, decide what to do, and write to the inverter loop every 5 seconds when new "devices/STAC/EnervenueBMS" data comes in. The writing is just to a single “Output Power Command” register on the inverter.
The Problem:
When enervenue_ctrlagent is installed and started, modbus reads of the inverter begin to fail. The controller’s attempts to write power setpoints are successful, but I start to receive this modbus_tk error (see the attached volttron_With_Controller.log):
Expected Behavior:
I was expecting that my controller agent should be able to run in tandem with the platform agent with no conflicts between reading and writing, but something funny is happening that I don’t understand.
Any and all help is greatly appreciated!
Joe Thompson
Engineer / Scientist
Electric Power Research Institute
Energy Storage and Distributed Generation
(912) 663-3407
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