Modbus over powerline


Thread Starter

Peter E

Does there exist a device which make it possible to transmit the Modbus over a power line ?

We got about 500 Canalis boxes from Schneider Electric in which we got some Modbus devices which we wood like to collect data from.

The Canalis box got a 5 wire high power plug, and a 3 wire low power plug.

I think about using the low power line for communication.
In the box i got 2 Modbus devices (a power meter and a Programming Logical Controller). These 2 devices wood i like to communicate with true wire (not wireless).

I know that there exist device for transmitting Ethernet over Power line, but does there exist device for transmitting Modbus signals over Power line?

Lynn August Linse

There are products out there - do a search for 'RS485 powerline'. Here is one example which even mentions Modbus.

My own small experience with powerline has been hit or miss. You'll find it either works well for you, or that 1/2 of your equipment will not talk well & you are left with a broken solution& angry customer. It depends on what AC loads are running on the same powerline & how much noise they inject of a particular nature!

For example, the old X10 powerline used in residential homes has been pretty much destroyed by compact-florescent bulbs, which inject so much noise on the homes AC wires that unless you pay for fancy high-power X10, it just doesn't work predictably anymore.

I have been exposed to restaurant use of powerline to monitor power & machine usage (McD's, etc), and that has proven a disaster to replicate. It works great in some restaurants; not at all in others. When it didn't work - who pays the $8000 bill to have installed & who gets blamed?

Also, using 1 pair of Powerline devices to tunnel Ethernet or TV in a home is one thing, but you are talking about 500 devices on industrial power lines? What kind of bandwidth will be available?

You need to do some serious testing before hand, and then pray that a 10-unit pilot test can scale up to 500. Note: with 500 devices (assuming all in 1 area?) even wireless/radio will be tough.

I'd suggest (if possible) that you do not think of your system as 1 system of 500 devices, but instead try to break into 10 systems of 50 (or 20 of 25), then use Ethernet between the systems. Those will scale much better.
I second the recommendation for some meaningful testing upfront and also the recommendation about making smaller networks and bridging between them, regardless of what network architecture you end up with.

Personally if it were me, I wouldn't even bother looking into the power-line carrier stuff unless the customer is demanding it.