Power supply and an IM483 Wiring Question

[sansbury]

Hi all:

Two closely-related questions as this is my first time using a bipolar driver and the IM483 as well.

First, the formular for PSU sizing as I understand it is 2/3 of the motor's rated current draw times the number of motors. My motors are the Keling 425oz which are rated as 2.8A bipolar-parallel, 2A unipolar, or 1.4A bipolar-series.

Thus, for 3 motors in b-parallel configuration, my recommended maximum size would be 5.6A, correct? (2.8 * 3 * 2/3) I have two 24V/6.5A PSUs and wondering if I need to use both or if I can run all three off of one. I don't want to buy a new PSU unless it's really necessary.

Second, I am trying to determine the right or best way to wire the IM-483s to my PC. The IM483 requires a separate +5V input for the optoisolators, with the ground side connected to the step/dir inputs. I have a spare 5VDC supply I was going to use. My understanding is that I would connect the +5 side to the opto supply on the IM483, and the GND side of the supply to the GND pins of the parallel port (should I tie them together or are they already tied?).

Thanks in advance!