wiring weirdness

[DerFarm]

I have no idea what forum to post this to, but its driving me crazy.

I'm using CNC Hat with RaspberryPi3.5. I'm attaching to Cloudray DS542 2-phase external drivers. They require 18-50V input (DC), output 1A-5A on the 4 output lines to the motors, 4 input lines from the computing source (PI) and two power lines (Live and Ground). My power source is delivering 47-49v on all 4 drivers.

My current CNC setup is a KRMx02 which outputs the pulses thru a cable to a DB9 terminal using lines 9,8,7 and 6 only. I bought 4 DB9 female terminals. They had wire entry openings so small, I could only use breadboard jumper wires to hook them up. I tested the wiring setup with a NEMA17 1.5A motor I had and it worked. The motor turned (YAAAAAAAAAAAA!!!). However, the motors I use on my CNC are NEMA 23 3.5A. Under the supposition that more is better, I got 4 DB9 female terminals that used much larger openings.

I received the larger DB9 terminals and hooked one up using AWG16 wire. This is the wire I use to power the drivers. I got a 'Driver OverCurrent" error. After an extensive session using highly technical terms, I re-worked the wiring using AWG18 wire. This is the size I used to wire the CNC Hat to the external drivers. Worked like a charm.

WHY??????????

BTW, BOTH the 16 and 18 are rated at 600V

[Bertus Kruger]

All I can think is a shorted wire or a wrongly hook up.

AWG16/18 should work the same up to max current rating.