Preffered Network? (lonworks, bacnet, etc.)

[toygasm4u]

Hey all. My company is exploring the possibility of getting some VFD's OEM'ed for our product line. We have the opportunity to populate the boards with whatever we want, and one desire is to make our VFD's networkable out of the box... so many selections!! We're very young into this project, but have been looking more at Lonworks as an option.

Our goal? To have a piece of equipment that will interface with the most popular communication protocols for building automation systems, energy management systems, and HVAC.

Based on you're all's experience, is there a network that stands to out perform, outlive, or is more popular than the rest?

Thanks for any input,
~M

 

[ScottyUK]

Ethernet will be around for a long time. That would be my preferred network. The components are cheap and widely available and it is very fast.

Modbus on multi-drop RS-485 is slower but has a huge installed base and is supported by a lot of products.


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Sometimes I only open my mouth to swap feet...

 

[ozmosis]

toygasm4u
Do not confuse the actual protocol with the network. The protocols you mention in your header (LonWorks, BACnet) can operate as TCP/IP or MS/TP so the mechanism will depend on your particular machine and then where you are looking to actually connect this machine. As Scotty points out, an ethernet connection is probably more future proof but currently there are no VFD companies who can connect with LON or BACnet direct with ethernet, they have to go via a router system.
For the protocol selection, LON is losing its hold in the HVAC business due to the relative high cost. If you wish to have devices that connect onto LON then each node requires a dedicated echelon chip, and this is pricey. BACnet doesn't and this seems to be the direction for most drive companies.
Most drives will have the choice these days of LON, BACnet, or even a propriety protocol like Johnson control N2 or Siemens P1(FLN).
Modbus is now an open protocl since Schneider 'released' it. This is low cost and simple to implement.
Summary:
From what I am seeing at the moment, BACnet would appear to be the one at the head of the game for VFD's. LON is behind and losing ground. Modbus is growing quickly now that it is 'open'. Most BAS systems out there will be flexible but as a VFD manufacturer, putting your money on one protocol horse is not a good bet, you need to be flexible and offer a few to suit the site in question. If your VFD is going into a site fixed on LON, then there is no way they are going to change anything just because your VFD cannot 'talk'.

 

[KiwiMace]

Good summary by sed2developer. I'd add that there are often multiple protocols at any given site.

Many owners are happy for their incompatible systems never to talk - eg. hvac doesn't need to share data with security - but in integrated systems, you can use gateways to transfer data btw the two systems. Companies like Tridium are strong in this, but in low complexity situations, you can add a point to point gateway to allow your data to cross the barrier.

Pick Bacnet or Modbus (as cheapest, or most requested) protocol, and build a LON when you prove your sales projections! Allow space on the PCB for the LON chip.

 

[toygasm4u]

Thank you sed2 for the summary. Do you think it would be safe for me to assume that if I have an ethernet based communication scheme, that I would have no problems communicating with others (Lon, Bacnet, etc.) as long as a gateway is in place? Or am I breaching on some kind of reverse compatibility issue?

I guess my real question is this:

If I'm running ethernet by default, will I

A) Be able to potentially control other devices via my network, and

B) Have the ability to control my drive from an existing network, be it Lon or Bacnet?

 

[ozmosis]

If you want the products to go straight onto the ethernet level, this is generally described at the "Automation Level" (certainly within BACnet land it is). Below this, it is referred to as the "Field Level" and products on this level are typically low level devices such as actuators, sensors and room controllers etc. Drives will often be at this level. For drives to get from the field level to Automation level (ethernet) requires a MS/TP router to ethernet. This is what all drive companies do at present. We are developing a direct ethernet connection into our drive but this will be 2 yrs away. I guess other VFD companies will be too but no sign of it yet.
A number of BAS (Building Automation Systems) that are either on LON can also communicate with BACnet and vice-versa. So, provided your VFD can communicate on either LON or BACnet, then this should not pose too many problems.
When you say 'other devices', what are they? higher level or low level field devices? low level like sensors/actuators are not typically connected on ethernet direct due to the cost and the fact you are sending low level info across the bus. A simple RS485 is usually enough then connect together in one of the sub-controllers and then this will shift it up the line to ethernet.
Some good info on

http://www.bacnet.org