OB115-MOD - 100 Amp Electricity Meter. MID Certified. RS485 Modbus. Includes Split Core CT with 2m Cable.

This is a nicely engineered 1 DIN module which has a clear display giving Import, Export and Total power plus voltage, frequency and Modbus settings.It's easy to read via Modbus since the registers are Float 32i not BCD.Owen Brothers support is very good too.

The unit works well and is easy to install. The first tip is: If you get a negative power factor reading with no PV being generated then swap the black and white wires to the current transducer.If you want to use the Modbus interface then the major problem is the poor documentation. The interface works fine but the description of the register values is just the number of bytes. Similar looking (EM-418) devices tell you that that data is BCD but this one is not BCD. The first seven register pairs (2&3, 4&5 etc) return a 4-byte IEE-754 floating point value. The data is big-endian. I assume that the Total Energy Accumulators are the same. The pulse outputs are via an isolated opto-coupler. This is probably an NPN transistor and it has an open collector so it must have a load to a +ve supply of 5 to 25volts. The load is 27mA maximum.