Problem- Are my motor and encoder cable is too long for self noise creation by Drive PWM.

[marq_torque]

Hi all

This is my first thread for CNC Zone, I am very thankful for all you guys for posting/solutions here. Though i am basically mechanical Er. i had my mind got cleared about all CNC automation like playing with servo tuning, encoder hooking up so on and on....


By the way here i got such unseen prob for my g320x series servo drive

My set up info:
Machine for : CNC Drilling/Micro drilling
CNC Controller soft : mach3
Axis drives type : Dc Brushed servo.
Encoders : Delta make Eh3 Line driver type 5-12v
Psu : 24v 10A SMPS from mean well
Axis travels : X-650mm, Y-2100mm, Z-150mm.


Though it seems appropriate i am facing problem like Error signal from gecko, at any instance gecko is giving error or some times it is running very pretty, i had tested all my mechanical system by hand, there is no jamming or fluctuation in smoothness of axis. even i can say motors have over power to shoot my axis. i have used cat5e 4-twisted pair LAN cable for encoder hooking, also tried shielded cable but cat5e given better result. there is no any certainty for error in gecko, i had added pull-up resistors for encoder which improved noise immunity specifically From VFD, though i had tried by switching off my VFD, Drives Still gives error at any time/or not giving, there is no other set up around this machine or noise creating equipments ...is this really a noise prob or anything else??

M getting very frustrated, even i had played with gecko many times in past, this set-up is not giving proper satisfaction/surety...

Tonight, i am going to change my motor cables to shielded ones.....

Let me check if it solves my prob. m posting if it is working or not

Help me out guys plz,

[marq_torque]

not good as expected for use of shielded cables for motors and encoders, also tried pull up resistor at gecko drive ....


But still same illness,

if use of differential line receiver for encoder signal be remedy for noise?????

my cable length is 7mtr/23ft

[ee_t]

A differential receiver would help. You could check the signal with an oscilloscope, to confirm the type of noise.

Bypassing encoder supply has been mentioned many times, but no idea if it applies to your particular model:

http://www.cnczone.com/forums/showthread.php?t=89079
http://www.cnczone.com/forums/showthread.php?t=73251

[Mariss Freimanis]

You are using a twisted pair cable. Make sure you aren't sending encoder Channel A and Channel B on the same twisted pair. Send GND and Channel A on one twisted pair, send Channel B and +5VDC on another twisted pair.

Mariss

[marq_torque]

thanks ee_t, morris
____________________________________________________________
To, Morssis

Sir,

As per my readings I am used 4-Pair Twisted cable like:

pairs are

1) Blue-White blue,
2) Brown-White brown,
3) Orange-White orange,
4) Greeen-White greeen

And are connected As :

Brown: 5v
Brown white: Shield

Blue: 0v
Blue white: Shield

Orange: Phase A
Orange white: -A

Greeen: Phase B
Greeen white: -B

Also my encoder supplier suggested to run -A and -B through whole length of cable and ground them to power supply of encoders.

But the real story comes here, when i am connecting the -A, -B, Shield and ground together at drive site drive doesn't come out of fault and when leaving -A and -B from ground and shield at drive site drive is normal locked out of fault, now on the other hand after leaving the -A and -B channels, at the time of running drive again giving fault randomly.


Some picture was clear to me when supplier suggested to run A and -A, B and -B through length. might it is going to shield my Channels from spikes glitches and random noise by creating loop to ground of supply.
but the picture is different, plz suggest me if i am doing wrong

also had idea that external power will solve the probs. as manufacturer informed in datasheet that encoder is consuming 100mA max might supply current of drive is less for that length.

And tested using 5-volt from computer's Extra HDD connector like:

5v : to Encoder
0v : to gecko, Encoder
and left the 5v terminal of gecko as i thought that drive senses encoder pulses ref to 0v

connected encoder channels as supplier told me but no result, also tried leaving -A and -B but the result is worst then connected with geckos!!! when switching on my VFD, Gecko starts giving me fault but when encoder power was connected with geckos the fault was less found then Power supplied by Computer!!!



Was thinking that computer's earth terminal and Vfd's Earth are going to same supply common that's why giving the noise!!!

Now i am going to morris's suggestion but thinking if the encoder supply current is an issue then this try will also fail !!!


Regards,

Ankit Mistry
Vadodara Guj,
India

[Al_The_Man]

Originally Posted by marq_torque __________________________________________________________ Also my encoder supplier suggested to run -A and -B through whole length of cable and ground them to power supply of encoders.

Why would you ground the A/ & B/ of the encoders? These transition between 0 and 5v with respect to common just as the A & B do.
This would essentially short the complements to ground.

Originally Posted by marq_torque ____________________________________________________________ Was thinking that computer's earth terminal and Vfd's Earth are going to same supply common that's why giving the noise!!!

I would suspect that the common grounding is insufficient if anything, you need to take the PC P.S. common and all shields and encoder power supply common to a central point including the service ground.
Have you also bonded the VFD and motor frame to the star point ground?
Al.

[marq_torque]

to, al the man


Oh My fuse blown...

Why did supplier given me that suggestion for grounding -A and -B i am just washed.

plz clear my doubt.

thanks Al

[marq_torque]

To, Al

Some thing is going ok...
today i used my cell phone charger for encoder supply which is rated @ 5.3v 530mA and working well but it is connected to Z axis encoder only! it was test if it works I'll buy 2 of them to power up my rest two Axis encoders!!!


Also changed Vfd's Supply terminal board

Problem is just disappeared now but there is one difference. when z-axis encoder was powered by gecko it was giving error, and when i connected external supply its working!
also i short circuited my -A and -B of encoder channel to 0v of P.S., i tried first by leaving it also worked well but was not sturdy as needed error was coming!!!

Pls tell me whatever i did is right or wrong!!!

basically i m mechanical er. yesterday i searched star ground practice and found my all wiring is OK!!!

[Al_The_Man]

You should be able to supply one separate supply for your encoders, only the commons of the encoders and the drives should be connected together.
To me, the A/ & B/ should be left unconnected if not used on a differential encoder.
Al.

[marq_torque]

I am tired of playing and playing...


Now all Z-Axis movements are ok but there are problems in X and Y Axis.

as did i mentioned that i didn't given PS to X and Y also tried my PS(530ma cell phone charger), parallel to all encoders but all of my drives show error when tried to run.!!!

also it is obvious that encoders are rated 100ma max and PS is530ma for 3 encoders!!! there should be no issues, but there is it!!!

This is my last post for this drives and motors, i am not going to waste my time and hard earned money for those hassling DC Servos where are many break points(Ps rating, Motor ratings, encoder combination, drive tuning, ....list is long for illiterate person like me). i am not sure enough to handle those.!! and trying to switch towards Panasonic AC servos if this is not going to work. i am not in condition to spend more time and money for this project what already i did.

thanking you guys for your replies and reading my posts. advises are most welcomed till this week.
only your experience can solve my prob. and save me from scrapping those 3 gecko drives, 3 brushed 24V 4A PMDC Servo motors, 3 Delta made 1024CPR encoders and 240watts MeanWell PSU

Waiting for your advice gurus

where are you!!!

[Al_The_Man]

Too bad you are having these problems, it is hard to give exact advice without exact details of your system and how your system is wired and laid out.
Generally a differential encoder set up is much less prone to interference problems, some of the problems may be eliminated by setting up a differential receiver on the the drive end, but I suspect there may be other issues with wiring and P.S. connections that may be the root of the problem.
It is very hard to tell from a distance.
Al.

[marq_torque]

Much Thanks al


for ur replies and time for my posts...


I did shifted to Fuji AC Servos. relpacing my older motor mounts to suit Fuji servos.

just Excepting it will work good. as local dealer provides after sales service i think there will be no failure, those guys installed the servos for 100ft long noisy distances.

Also building micro lathe from that Geckos and DC servos. no need to crap those.!!!



Updates will be soon in build forum

cheers