[ModBusMaster port for Spark] Connecting to Power Meter with RS485


#1

Hi there

I working on a project to connect a power meter that is on RS485 to spark core. The idea is to have spark core take the reading. I search around the forum and found the following library.

ModBusMaster port for Spark
But I’m not very good with this RS485 and I like seek some advise from members around here.

Currently the power meter is connected to a PI via a RS485 to USB. I thinking of changing the pi to sparkcore.

This is the power meter I’m working on

It is a Mitsubishi Electric Energy Meter.
The model is ME96NSR.

The internal wiring connected

I have the T/R+ and T/R- leading out to a single wire. This wire will be for TX and RX.
The orange wire goes to T/R+ and the blue cable goes to T/R-

The other end was connected to a RS485 to USB


But I have since remove it.

If I’m running the above library, how should I connect the wire so that I can get a reading via serial?

Which pin should the orange (T/R+) and blue (T/R-) go to respectively?
Currently the meter is set to slave ID 1.
If any one could point me to “hello world” kind of tutorial for RS485 to spark core that would be great too :smiley:

Thank you so much.


RS-485 modbus library
#2

My best bet would be to use an off-the-shelf 3V3 RS485 transceiver chip like the max3485

And for wiring have a look here
http://sourceforge.net/p/arduino-icsc/wiki/RS-485/