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View Full Version : switching from steppers to servos - STEP / DIR control



dsc
08-04-2014, 12:54 PM
I'll probably be switching from a 12Nm stepper to a 400W servo with a gearbox, as I need more torque over a wide range of speeds. Curious how many people here used servos before? I'm mostly curious about STEP / DIR control as the voltages mentioned in the manual are anything between 12 - 24VDC, so I can't connect the PIC directly to the driver. I'm thinking optocouplers with an outside 12VDC would work (triggered by the PWM pin output from the PIC), but the analogue -/+10VDC input for speed control looks interesting as well.

This is the driver and motor:

http://www.leadshine.com/UploadFile/Down/EL5-Md.pdf

http://www.leadshine.com/UploadFile/Down/LSC_High_Voltage_Servos.pdf

Any tips would be very helpful.

Regards,
T.

m_c
09-04-2014, 12:52 AM
I've never paid much attention to the leadshine servos, however I use Kinco servos and drives.
I'm sure the kinco servo drives (zapp sell them) will work from a 5V source, and certainly the newer range can be programmed to do various things just using the standard inputs as triggers. Might be worth downloading the manual and having a look to see if it will what you need without the pic?

Ger21
09-04-2014, 01:01 AM
I plan on using the Leadshine ACM series servos. Virtually identical specs to the EL5, but they run on 60VDC instead of 220AC.
The ACM servos take 5V step and direction.
Leadshine Technology Co., Ltd. (http://www.leadshine.com/productdetail.aspx?type=products&category=servo-products&producttype=brushless-servo-motors&series=ACM&model=ACM604V60)

dsc
09-04-2014, 08:08 PM
Thanks Gents, I'm not 100% it needs 12-24VDC, I couldn't find a full manual for those drives, just the PDFs on Leadshine's website, although those seem more like catalogue data rather than a proper manual.

Ger21, I can see 5VDC shown in the motor cable table, but how do you know the driver takes 5VDC as well?

Regards,
T.

Ger21
09-04-2014, 08:37 PM
The Manual for the ACS drives specifies 5V step/Dir.

dsc
28-04-2014, 02:43 PM
Ok I got the driver and motor now, damn this is quick and quiet and small overall, toy like almost! also got what seems like a working copy version of the manual from Leadshine.

I can run it in position mode by using the STEP / DIR, these indeed take 5VDC. There's also a velocity mode, which takes a -10VDC to 10VDC and you can configure the drive to pretty much any speed / voltage ration, default is 500RPM per 1VDC, so 6VDC for max speed. I can change that to 600RPM which will allow me to use a PWM output from the PIC and deliver 0-5VDC to get 0 - 3000RPM (hopefully).

The downside is that it still needs 12-24VDC to enable the driver and servo, these inputs don't take 5VDC, but I've already ordered some ULN2003 Darlington arrays which should allow me to drive 12VDC inputs via PIC output. Also not sure how well the driver operates in open loop control, it does have velocity / position outputs, but I wasn't really planning on using those for closed loop control (just deliver the full 5VDC and hopefully get 3000RPM).

Regards,
dsc.

dsc
18-06-2014, 01:41 PM
Quick update just in case anyone uses Leadshine servos in the future. Hook up is pretty simple, you just need a pot 0-5VDC to set the speed (configure the speed input to be 0VDC => 0RPM and 5VDC => 3000RPM), 12VDC and some transistors (or the mentioned ULN2003 array) to drive the enable input on the servo controller. I'm using a PIC to toggle the enable transistor and the servo runs of a 13A plug, via an AC filter.

Regards,
dsc.