there is a fundamental difference between wiring a Honeywell HART based Pressure or Flow Transmitter installation versus wring a Honeywell Digitally Enhanced (DE) based Pressure or Flow Transmitter installation
The HART communication signal is comprised of a AC sine wave signal with an amplitude of +/- 0.5 mA and with a frequency of 1100 and 2200 Hz. As a result, wire capacitance is of primary concern in a HART based transmitter installation. Therefore in a HART based transmitter installation cable lengths with differing cable core sizes, and cable capacitance are important.
The DE signal is considered a DC square wave signal with amplitude of 20mA and as a result wiring impedance is of primary concern. Too much wring impedance, which is directly related to wiring length and gauge will reduce the voltage available to the transmitter. Therefore in a (DE) transmitter installation larger gauge wire is recommended to reduce loop impedance