Hi everyone,

I bought a Leadshine EL5-D1000 driver and matching 1000W motor (just 1 to try out, and I am glad I didn't buy in bulk). It has a number of inputs and features, but I was just looking for a low-cost 240V torque controller and was planning on using a Kanalog +/-10V single ended output to control it.

I was having a heck of a time tuning the motor without a load attached to learn how the driver behaved under torque control. After hooking the motor up to the ballscrew I discovered the problem with using the single ended output onto the driver's differential input: when reversing the Kanalog DAC polarity the motor will spin in the wrong direction for a while before eventually proceeding in the correct direction. Without the drag of the ballscrew and linear bearings it was just taking off into unstable cycling as soon as the Kanalog reversed polarity and I couldn't figure out what was happening exactly, with the ballscrew attached it looks to turn in the wrong direction for about a quarter turn before coming around, under a constant (minimal so as to keep it slow) DAC output with a DAC(0,60) type command. I can attach a graph if that is helpful.

The servo driver manual shows pins 39/41 were for single ended inputs and 43/44 were for differential inputs (see attachment), but there is no way to choose which one is used for the controlling input (based on context I suspected that parameter pr317 might control this, but it is omitted from the description table in the manual) as per their support:

Hi , I just discuss with RD teammate , torque control is only available with analog input from P43&44 ,and the input range is -10 ~ +10v ，positive means CW and negative means CCW .
About pr317 , 0 is for your application , no need to change to 1 or 2 , sorry i have no details about this parameter now .

BTW, which country are you from ? from US ?

Best regards
clark
product&technical engineer
Leadshine Technology Co., Ltd.

Address: 11/F, Block A3, iPark, No.1001 Xueyuan Blvd.
Nanshan District, Shenzhen, China www.leadshine.com


(this response is unsatisfying, as is the claim that they have US support when I bought it on americanmotiontech.com, it arrived direct from China after claiming it was out of stock once the order was placed as well.)

So my conundrum now is how to move forward. Options I see are:

1) Switch the servo driver over to velocity mode on the single ended analog in pins and only set the P parameter in the driver (which is sort of equivalent to torque mode with extra time lag as it goes through the PID loop in the servo drive?)
2) Try and get the step/dir function of the KFLOP working to control it (which I hadn't been planning on using for any of my setup)
3) Get a single ended to differential IC chip and wire that up externally
4) (some handwaving involved by a ME trying to do EE stuff here) Use two DAC channels to create a differential signal as I only need 5 out of the 8 channels.

Which is the best option from a controls perspective for 1-4? 1 seems the simplest if it would work well enough; I am going to try a different vendor for the rest of the axes, maybe DMM.

Thanks,
Andy