I can't find a datasheet on the sensor. Here's a link to it. It has two pulse outputs, but it doesn't specify much else
http://tctsolar.com/tctmetrima.htm
As for the ModBus, what type of specs would be helpful? It's a WattNode ModBus. It measures current, voltage, frequency, etc.
UPDATE:
Based on a spec sheet I found, the pulse outputs for the Metrima are "open collector" types and have specs as follows:
Pulse duration 250 ms
Max. voltage 30 V
Max. current 20 mA