Monday, 13 November 2017

Leadshine DM556 stepper drive for 4th axis - real or fake??

The "Leadshine" DM556 stepper drive I ordered last week arrived this morning. This is a 50V / 5.6A 2-phase stepper drive.

Given that it cost around half of the price I'd have paid through official distributors, I'm expecting it to be somewhere between hot (back of a lorry / factory door) and a clone (knock-off). There's a whole spectrum of possibilities including genuine product at local China prices, factory rejects, "extra" but unofficial production runs at the factory, clone rip-offs of the real product, through to completely different drives with a Leadshine logo stuck on the front. What will it be?

This is all I got (no instructions, fixings, bag etc:



Obviously the first thing I did was to render the "warranty"(??) void by removing the cover to see what was inside.



It's pretty nicely made and like most drives these days, it's very compact. The main body is a length of extrusion with a moulded plastic cover held on by 2 screws. Underneath is a single PCBA with everything on it. Obviously there are some power devices that have to connect to the PCB and mount onto the heatsink. I'm not expecting any surprises here - and sure enough they are simply TO-220 devices, held up against the heatsink by the PCB, itself held down by some screws. So the PCB is the spring element. Insulation is a simple matter of some Silpad-like thermal material.

Functionally there are no surprises either:


Internal PSU:

  • Good old fashioned UC3843B PWM controller, originally by TI / Eunuch Toad. Actually made by ST.
  • Flyback transformer driven by IRFR22N (200V 600mR) MOSFET
  • AMS1117 LDO regulator, providing 3.3V for the logic circuit.

DSP / microcontroller / logic:
  • Good old fashioned TMS320F28027(??) "Piccolo" DSP for all the software and I/O. Hard to read the exact part number, as there is a big tick mark on the top face. It seems to be a QFP48 package which seems to rule out the 2803 but I'm not that bothered about getting the part number correctly identified. Whatever - I'm close enough. It's a TMS320 C2000 DSP.
  • Atmel ATMLHS16(??) serial EPROM.
  • 6N137 high speed digital opto (x2) for the Step / Dir inputs.
  • Another opto from Sharp (can't read it), presumably a cheap, low frequency thing for the output status / fault output.
Power stage:
  • 8 x IRF540 (MOSFET TO-220 package), forming 2 full bridge outputs - no obvious manufacturer but these are such an old design that almost anyone will claim to be able to make them.
  • Level shifting high side / low side gate driver (x4) from International Rectumfrier IRS2104. Nothing special there - nice, simple, robust things. I must be out of touch now but it seems that Infineon are now holding the IR brand. IR seem to flog off part of their portfolio periodically for some reason.
  • A couple of 220uF 63V electrolytics by "Jwco". There are a few electrolytics on the board, either by them or by "Chang".


Under the PCB:
  • Various TTL devices:
  • Unbranded 4052 (CMOS analog multiplexer / demultiplexer). Presumably they needed more analogue inputs than the DSP came with.
  • Several other 74 and 4000 series devices in DIP packages.




Also:
  • Device U4 has had its top shaved off, presumably in a bid to prevent easy cloning. It's a 14 pin device but not with the normal TTL / CMOS power connections on pins 7 and 14, so presumably a little less commonplace. Unless it's a Leadshine proprietary device, I can't imagine it would be massively difficult to figure out but I guess it will delay or impede the really crap clone outfits. Of course, if it were proprietary, there would be no need to shave off the part number.....
  • 20mR current sense resistors on each phase. 
  • Lots of shitty looking 100nF film caps all over the shop. But at least they have fitted a fair bit of decoupling which is good, seeing as it will be a fairly noisy circuit.
  • The PCB appears to show a date code of "06 17" (2017, week 6), in which case, this would be a very recent product.
Externally:
  • The QR barcode shows "leisai.net", which seems to be the (Chinese language) Leadshine website. 
  • Completely unsealed housing. Nicely made and assembled for the budget.
  • Removable green signal / power connectors, as is the norm for this kind of product.
  • No box, instructions, bag etc (from this ebay supplier!).
Conclusion:
  • Looks like either a genuine article from Leadshine, judging by the quality of the construction or simply a very close clone. I have no 100% genuine example to compare against.
  • The construction and design look about right for this kind of product ie mainly hobby / "semi-professional" (at best). It certainly isn't proper industrial and I wouldn't expect it to last long in an industrial application. It is of similar overall quality to the DMM Tech servo drives I have for my BP conversion. No complaints.
Right, enough armchair engineering. Need to get something real done at some point.

1 comment:

  1. How to wire 3 axis with DM556. I do have also 3 of these drivers with Power supply (350 watt 36v dc). But I don't get the DIP switch setting (what is ideal setting) with 6 wire old printer motor. Any guide is appreciated. Thank You Sir.

    ReplyDelete

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