Lonworks vs Other Technologies.


Thread Starter

Steven Landau

I have a lot of experience with all sorts of PLC's (AB & Modicon) and Scada (WW/iFix. etc). and Delta-V

I have looked carefully at the $ per I/O point which I can get from a PLC vendor, vs. the Application Specific HW available for Air Handler/HVAC control, and find the HVAC HW significantly less expensive, but programming
is more cumbersome. E.g. direct input for very low cost but accurate thermistors.

We have found custom function blocks in IEC1131 a lot easier to deal with than the Lonworks equipment.

Have any list members used a lonworks system for HVAC control? And have had a good experience with it vs. PLC's?

Ideally I would need distributed control, connected by a network, to single HMI. Where it is easy to duplicate code among nodes. Use relative addressing for HMI tags, all the things which lonworks promises to offer, but with real programmability at each node.

If you have evaluated these technologies for HVAC control, and have come up with HW/SW solution, which a DCS/PLC engineering would find usable, please feel free to contact me off-list for further discussions.

Steven Landau
VP Controls & Automation
SPEC process engineering & construction
92 Montvale Ave
Stoneham, MA 02180
T. 7814383337
F. 7814385297

Dave Millett


My background is in control systems for HVAC, and I am moving the other way - towards PLC's! My main experience is with Trend Controls, a UK-based supplier.

Their equipment consists of a series of programmable outstations, with I/O counts from 6 to 96 depending on the model. These sit on a 2-core ring network (I believe RS 485) using a proprietary protocol.

Trend also supply lonworks-compatible programmable controllers, usually with a low I/O count, which are aimed specifically for HVAC terminal units such as VAV boxes and fan coils.

You are used to ladder logic with programmable blocks. Trend software uses configurable modules that are linked together - the output of module feeds inputs of other modules. Modules include a wide range of analogue and digital functions, PID loops, time controls and inter-controller communications. One difference is that you specify the sequence in which modules are operated - there is no fixed order as there is in a ladder.

Remote support via modem is far easier than for PLC's. From my desk I can dial up any of the sites I support, view data, adjust setpoints and even re-write the software.

Their website is www.trend-controls.com, and their US distributor is listed as:

The Germinsky Group
200-214 West 4th Street
PO Box 1366
NJ 07061
Telephone: +1 908 412 3520
Facsimile: +1 908 756 3636

The company I work for now uses Trend or PLC's for plant controls, usually steam boilers, generators, CHP plant, compressors etc. We only use PLC's for the most complex sites, or where bought-in kit already has a PLC, such as
engine controls for generators. Trend kit is surprisingly powerful and flexible.

One word of advice. Trend provide their own HMI software, but it is rather expensive. I use a simpler application called Doorway, that can be engineered into a full graphical HMI, with data logging and recording. List price is about

Hope this is some help. Feel free to contact me at [email protected]

Dave Millett
Area Systems Engineer, North West


Walt Flannagan

PLC's. We do both. PLC is my preference 11 times out of 10. You have a open platform for programming, your not just filling in the blanks (duct size, flow rate, etc...) and pressing go. Although that may sound easy, I find it

All of the things you wish to do with Lonworks based DDC controllers are very simple with the right hardware/ software. I mainly work with Invensys I/A series controllers and the associated node programming software for HVAC
applications. The programming interface is very easy to work with (provided you're familiar with visio). It runs ontop of visio 5.0 and 2000 Technical and has the same interface. you can drag and drop all of your programming objects
onto the page and just connect the wires. As far as HMIs go, we've had really good luck with Tridium's niagara. You can use it to integrate various control networks (including LonWorks) and present the data in a java applett that resides in a web page. if you are interested check out "http://www.tridium.com/":www.tridium.com and "http://www.invensysbuildings.com/ia/":http://www.invensysbuildings.com/ia/

If you have any further questions you can email me [email protected]
hope that helps

Martin Pauley

I have had major sucess in intergrating
Honeywell EBI with a third party lonworks VAV
and FanCoil Controllers using the LNS database
and EBI point server,as well as intergrating
Rockwell's RSview using OPS as the HMI as part
of the design specs.
I have found that the new Honeywell tools make the Exl 50 ver 2.6 firmware very easily into intergate directly to the LON network.
I have also used the Trend System with third pary
Lon device and was suceesful although
the programming time goes up, you don't pay any
credits to Echelon as TREND uses the Lonc and
IC comms to map the SNTV.
Enviroware Construction.
South Africa.