I have researched the internet and can only find Modbus RTU Trunkline taps for 2 wire Modbus serial. I need 4 wire Modbus taps. I am using gas detection equipment with 4 wire Modbus RTU output. The output is powered from the transmitter. How do I wire this into the trunkline? I am in a classified area, Class 1, Division 2 (oil refinery). Is there anyone that makes field mounted 'taps' that can be installed along the trunkline?