This project reads out several S0 outputs from power meters and dumps the calculated wattage for each of them to serial.
Connect the positive sides of the S0 outputs to the same I/O port on the Arduino. Also connect these inputs to +5V with a pull-up resistor. Connect the negative sides of the S0 outputs to the Arduino's ground.
Check that NUM_INPUTS, INPUT_PIN and PULSE_ENERGY are correct for your setup.
Each pulse triggers an output of the form:
n: x W
n
is the input ID (bit on the I/O port)x
is the current wattage or N/A for the first pulse (so you can still count pulses if you want)- W is the unit, watts