MooveInd

Hi Ivan,  Completely agree with you comments on using comms protocols and twisted pair, will be using this method on future projects. We did try using preset positioning in the ASADA A2 drive, triggering each movement by RS485, the positioning was very repeatable, but we found it to be very laggy in both starting the move and the completion flag. The particular model of the drives we have ASD-A2-0421-L don't have Ethercat, CanOpen or DMCNET so I couldn't see any other option for variable positioning control? The cable length was something I didnt mention in the beginning as we originally had the pulse/direction bundled in with the other input/outputs in a 20 or 30c cable (non shielded). Our first thought was to change to shielded cable for the pulse/com so we did that, which still didnt solve the problem. Based on that change I had asumed (seemingly wrongly) that we had eliminated the cause being the cable. Hopefully the conversation in this thread gives someone experiencing a similar problem different areas to look! Apreciate yours and everyone else's help.

How far away from the PLC was the servo drive? The post from Pturmel has me thinking the issue in my application has largely been caused by the length of cable from PLC to drive, which in my Delts DVP applications has all been quite long. This was not the case where we have used either the Mitsubishi or Innovance PLC/servo combinations with no issues.

Hi all, so the issue was ongoing and we ended up with a new Delta DVP ES3 PLC having the same issues with the Innovance drives. Changed the drive to a Delta ASDA A2 and alas, no better. After digging deeper we noted the ES3 manual shows the need for a zenner diode + diode in parallel around the load. Something we were familiar with for inductive loads, but had no experience with on pulse train outputs. See attached. Running positioning instructions at 150k with no issues now! Will implement on our ES2 PLC's and see if it resolves the problem there also.   Diode.pdf

I share your thoughts on the inovance experience in general....poorly copied Delta products.. You are right on the transisters being binary state. We have ruled out noise as the issue for the following reasons (correct me if i'm wrong) we have tested with 2 different wiring setups, first was non shielded, then we went to shielded twisted pair, with no difference in the error. Secondly the error increases in a linear fashion as we increase the frequency of the pulse train. I wouldn't have thought noise would be so consistent and repeatable? Thanks for your help.

really good thought, I dont have an oscilloscope, but it might be the time to invest in one. Do you have any other thoughts on how the Inovance drive could count aditional pulses from the delta output?

Hi Ivan, Thanks for your reply. Unfortunately we have 6 of the inovance drives, so its either I fork out to change all of those to delta drives, or we change the Delta PLC's to either Mitsubishi or Inovance (too much re-programming for my liking). Agree with your comments, in the applications where we have Delta PLC to Delta Servo drive it is working perfectly. As is Inovance PLC to Inovance Drive  We have confirmed that as the speed of the pulse output increases, the numer of additional pulses the inovance drive counts also increases. Given this is a somewhat linear relationship we concluded it can't be signal noise related. Perhaps something to do with the shape of the pulse output from the delta PLC.  

We currently have Delta DVP60ES2 and DVP32ES3 PLC's doing positioning control on Inovance IS 620PS2R8I 400w Servo Drives by Pulse/Direction. Under both of these environments our pulse count read on the Inovance drives are reading higher than what the PLC is outputting. We also have Mitsubishi & Inovance PLCs, which when connected to the same Inovance drives dont have any discrepancies in the pulse count. We also have Delta ASDA servo drives, which when connected to the Delta DVP PLC's also don't have any discrepancies. Given we have tested these combinations, it has led us to believe there is something unique about the pulse train output from the DVP PLC's that is causing the Inovance drives to read additional pulses. Has anyone experinced a similar issue with Delta PLC pulse output? If so what was the solution? 

Wonderful, thanks for your help Wasan!  I disabled the wireless card and set-up the IP on the USB-Ethernet adapter. Thankyou.

I'm using a USB to Ethernet adapter on my PC, however the adapter does not show up in the list of Ethernet cards in COMMGR.  Does anyone have experience using USB to Ethernet adapters for Ethernet communication with Delta PLC's? Hardware config on my PC shows the USB adapter as a network card, DCIsoft will successfully find the connected PLC (DVP60ES2-E)