Looking to make a low cost power data acquisition system. Wondering if there is a low cost modbus meter for under $100. Just need a basic one that can give the power/energy measurement via modbus. My goal is to create a complete system, meter+datalogger+gateway for <$200.
Any pointers would be great.
I was not able to tell whether you need 3-phase or single-phase and whether this is for your own personal use or to be offered for sale.
But there is a power metering device that already does all of what I understand you are looking for (Metering, Data Logging, Modbus, 100BaseT Gateway).
EIG Shark 200 and Shark 200T...
I don't know the cost, but I'm sure it's more than $200.
The Accuvim II might be another option...
Thanks for the reply. But the Shark and Accuvim are all very very expensive. I have used the Shark100 and some other intelligent meters. All are over $300.
I think there is a need in the market for a very low cost non-utility grade meter. Meaning even if its around 5% accurate its ok. As long as it provides some type of data interface for its contents to be read/written to. Modbus TCP support would be the best.
My design objectives are to bring the cost down to below $200. Is it possible today?
I'm glad that u try to do that same thing for an Eco building I'm consulting for a client, so I'm trying to do like your issue. I've used the following: a device smiler to Accuvim, but noname (from China). also I've attached to it a Modbus. I can read the device with their software remotely, but I want to post that online via my own PHP server. then I got download a PHP code module called (Phpmodbus), but I couldn't run it successfully. do u have any success in your project? may be we can exchange ideas?
We do offer such very low cost modbus meter, please feel free to contact us: http://www.stitcs.com
You can try with a low-cost Modbus TCP counter device from http://lowcostio.com with any low-cost digital meter with pulse output.
It's easier, and potentially more accurate if you don't care about Real versus Apparent power.
Continental Control Systems has 0 to 0.333VAC touch-safe CTs. Offset that output by 2.5VDC, then amplify to 0 to 5VDC. Now you've got a signal that has plenty of range and can be read directly by any of the small uMCes on the market. Pick a sampling interval that's plenty fast and produce the RMS current. Hard-code the AC line voltage, ignore real versus apparent power, and the as-manufactured cost is under US$100.
Walk in the park.