I bought a 3-axis CNC kit from Zapp about 18 months ago but have only just got around to putting it all together. I noticed that Zapp still sell this kit, however the components have now changed. Although the wiring looks fairly straight forward, I have a number of questions. And if I'm honest, I'm shitting myself because I don't want to switch the power on and see my hard-earned disappear in a puff of smoke!

My electronics are as follows:

PSU 1: 24V DC (used to power the BOB and safety circuits)
PSU 2: 50V DC. Datasheet HERE
Stepper Drives: PM542 (unbranded...NOT Leadshine). Datasheet HERE
Stepper Motors: SY60STH86-3008BF. Datasheet HERE
BOB: Diycnc PCPPS V3. Datasheet HERE

Please bear in mind that I'm a complete newbie to stepper drive systems, however I do have experience with industrial electrics such as AC motors and drives, safety circuits, PLCs, etc. I'm rigging up the X-axis on the bench to prove the system before going for the finished build. My questions are as follows:


1. The 50V PSU is only outputting 42.7V. To quote from the datasheet (P4.1): "Note: If the PSU is out of regulation then Uout=42.8+/-0.5V". So there's nothing "wrong" as such, however the DC output is supposed to be 50.5VDC – 56.5VDC. Noting that the PM542 drives have a maximum voltage of 50V, should I actually attempt to use 50V? If so, how do I get this darn PSU into regulation/50V mode?


2. How do I wire the steppers to the drivers? I believe I should be aiming for Bipolar Parallel. The datasheet is a little confusing as the "Bipolar Parallel" diagram seems to confuse the * and - of the coils, for instance showing one end of "C" as both * AND - with the other end simply marked "C". After some head scratching, this is my interpretation:

Join A* to C* and connect to A+ on the drive
Join A- to C- and connect to A- on the drive
Join B* to D* and connect to B+ on the drive
Join B- to D- and connect to B- on the drive

In wire colours, this equates to:

Blue/White & Red = A+
Blue & Red/White = A-
Green/White & Black = B+
Green & Black/White = B-

The datasheet diagram appears to have the phases opposing (i.e. A* to C-, A- to C*, etc) but that seems incorrect to me??


3. Assuming the PM542 now has the following connections: motor wired as above, 42V supply, PUL+, PUL-, DIR+, DIR-, ENA+ and ENA- from the BOB, what switch configuration should I use? My interpretation is as follows:

To set 4.2A peak current: SW1 = off, SW2 = off, SW3 = off.
To set half current: SW4 = off. (or should I use full current??)
To set 1600 pulses per rev: SW5 = off, SW6 = off, SW7 = on, SW8 = on.

How many pulses/rev should I use? Or is it a case of trial and error to get the best/smoothest performance?
Do I even need the ENA connections?


4. Assuming I now have everything wired up OK...how do I test my X axis? Do I have to use the computer, or will the "force" jumper on the PCPPS BOB enable me to run the motor temporarily?


5. As someone who has not used Windows for 5+ years, EMC2 is going to be my control software of choice. I've not used it (or any other CNC software!) before, so could be a steepish learning curve. Does anyone here have experience with the EMC software? In particular, I'm wondering what the hell I'm supposed to to with the configuration wizard as I don't have much idea of what numbers I need to enter. Can I use a default config or will I need to create a custom one to suit my hardware setup?


Apologies for all the questions, though I'm sure you all asked these once upon a time.