(1) You have the step/drir "COM" terminal wired to the positive puse/dir pins, but your profile has the "step/dir com" set to GND. Go into the PMDX plug-in configuration on the "motors" tab and select "Step/dir common i s+5V". And while you are there, change the "Step" and "dir" polarity from "positive" to "negative". The step polarity wouldn't keep the motors from working, but with +5V common, "negative" step/dir polarity is the correct setting. Though, depending on how you have your motors wired, you may want to change your "dir" polarity back to positive to get the motion in the desired direction. But leave "step" polarity as negative.
(2) The data sheet for the DM542T is a tad confusing to me as to which polarity enables the driver. Though it does say they recommend you leave tne ENA+/ENA- terminal unconnected to enable the drive. So I suggest you try unconnecting the ENA+/ENA- terminals.
If that doesn't work, try slowing the acceleration way down in the main configuration motor config tab.