ModBus - ModBus Plus - LONWorks


Thread Starter


I am trying to understand the inter-working of a power generation system (ONAN/Cummins)that uses ModBus, ModBus Plus and LONWorks. We have VERY little network documentation for the system, and are having issues with the LONWorks part of the system.I am trying to figure out what controls/alarms we might be missing with part of the network scheme disabled?

Thanks for any help you might be able to give me.

rac [at]
I think that this issue arises because Cummins uses compressor controls with LonWorks protocols. You will have to determine which registers in the Cummings are important and then get a gateway to move Modbus messages to/from these registers on the Lonworks side. Schneider did (still does?) provide a Lonworks card for the Quantum PLC. The gateway will have to be configured.

Wassim Daoud


what kind of issues are you experiencing? are you using OPC?

Looking forward to hearing from you


Wassim Daoud
Global Solutions Architect

Fred Loveless

I see this all the time. Now that the industry is using standardized communications between servers and client applications you no long see facilities using just one manufacturer for all hardware in the plant. Also Power management is the last thing to get done in some facilities or it is done in phase and the technology in the monitoring devices changes over time. I am really surprised you have not run into DNP3.0 as well. Anyway I have a lot of customers that are using various Lonworks to Modbus converters and I have not heard of any issues yet. Keep in mind hat you don't hit these devices with 10 or 100 msec polls they are designed for slower polling.

Fred Loveless
Applications Manager
Kepware Technologies
This not a simple solution, Cummins have a Lonworks/Modbus translete, ModLon I and ModLon II, that need a lonworks stencil to say at modlon what do you want, comunication with a transfer system, small, medium o large generation (power Command 2100, 3100 or 3200), then you need configurtaion modlon for modbus protocolo (speed, parity, stop bit, protocol, address and so on).

Lonworks for quantum I´m not know if work to this aplication. I use a momentum and/or quantum modbus port and xxmit instruction in Concept.

But first i configure the Lonwork network with Echelon LonMaker and Microsoft Visio software, using a PCMCIA interface.

Obvious Cummins equipment need have a lonworks module, because that is an accessory
Dear All,

Do you know how to communicate Modbus RTU through PLC ( OMRON, Siemens ..) to take all data from Cummins Genset (PCC2300, ..)

Loytec has a L-INX Automation server that can bring in the LON data and you can connect it to Modbus RTU or TCP. It can be a slave or master and also automatically generates OPC tags (OPC XML/DA) as it is also has a built in OPC server.

It does more than gateway, but this gets you where you want to go. Loytec does not use a Neuron chip in their LON side. They developed their own implementation which means more variables than others solutions.

You should be able to scan the LON equipment from the device and bring in the variables or make binds.... so at least for this LON is significantly better than Modbus RTU.