Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....Still there....
Posted by
Babar
on 2002-09-14 05:05:59 UTC
>Do you ever disable the 26LS31? (which is what Iknow the
> SN75174 as in this part of the world)John, We already have connected the Active High Enable
> Better not to here.
signals of 75174
(pins 4 & 12) to Vcc=+5V
please tell us what do u mean by disabling the 26LS31?
>Is the pair terminated (ie ~100 ohms across it) atthe load end
> well worth doing!/A output pins
> (the pair is the two wires connecting the the A and
> through to the far end)No we havent terminated the pair of each encoder
outputs.
And if we need to terminate it then the best place
which i understand is at the inputs of receiver ic
"26LS32" present on STG-II. meaning we
will have to solder the resistors on STG-II??
>Is the pair run as a twisted pair?The cable that is coming from encoders is a 13 core
> helps, but depends on your wiring.
sheileded cable. out of which 8 wires are being used.
the Sheild is connected to system earth + ground. this
sheild is connected to ground only at single side.
Now this cable which has differential signals come to
a board from where it goes to STG-II using simple
ribbon cable (not shielded).
This board also contains connections for DAC outputs
of STG-II.
>Do you use a 26LS32 or similar to receive thedifferential signal?
> essentialNo we use 75174 ic at encoder side and since STG-II
can accept differential signals therfore we didnt use
any Receiver ic.
>do you have any test equpiment (eg oscilloscope) tomeasure
>noise levels?We have osciloscope. but We have rarely seen noise on
osciloscope.
although the stg2diag shows big errornous values
following is the respone of stg2diag utility:
[root@localhost bin]# stg2diag
Servo To Go Board IO address = 0x200
+1.000 +1.000 -2.000
+1.000 +1.000 -65538.000
+1.000 +1.000 -2.000
+1.000 +1.000 -65538.000
+1.000 +1.000 -2.000
+65537.000 +65537.000 -65538.000
+1.000 +1.000 -2.000
+65537.000 +65537.000 -65538.000
+1.000 +1.000 -2.000
+65537.000 +65537.000 -258.000
+1.000 +1.000 -2.000
+1.000 +1.000 -65538.000
+1.000 -3.000 -2.000
+1.000 -3.000 -65538.000
+1.000 -3.000 -2.000
+1.000 -3.000 -65538.000
+1.000 -3.000 -2.000
+65537.000 -131075.000 -65538.000
+1.000 -3.000 -2.000
+65537.000 -131075.000 -65538.000
+1.000 -3.000 -2.000
+65537.000 -131075.000 -258.000
+1.000 -3.000 -2.000
+1.000 -3.000 -65538.000
Looking at this response we see big errornous values
after which
the next value is same as before the erroronous value.
Isnt this shows that this problem is perhaps something
to do with the software?
I meant if the actual problem is with errornous counts
originating
form encoder, then why these counter do not retain
that errornous
value?
Les you wrote:
>With computer ON, encoder supply ON, and servo ampsOFF (at supply)
>does the encoder count still smoothly change when themotors
>are turned by hand with all axes?problem appear
>If so when the servo amp is turned on does the
>with all axes? (of course it should have 0 input whenturning it on)
>Does the problem disappear if the servo amps are onbut not enabled?
>Is the behavior noticed with BOTH EMC and stgdiagprograms?
We used external supply this time thinking that this
might help us. isolating this encoder power suply from
the machine. Our computer was
ON servo amps and all the machine supplies were OFF.
What we saw on STG2DIAG noise such as shwon in above
response. We ran the EMC,
run the motors with hands and didnt observed Counter
stucking problem.
Here please note that when the drives are powered, pc
is ON and EMC running, When we run any axis drives
using Testing dialog box then for
upto 3 volts counters dont stuck (Although we see
continous errornous big values in stg2diag)but for
more than this 3 volts counters stop.
To do this check we run stg2diag in parallel with EMC.
When Stg2diag program is running it never stucks
counters but gives
errornous big values after some random period of time
which is around
1 to 3 seconds.
>Can you download the DOS version of stgdiag and runit from a >temporary
>DOS boot floppy? If so what are the results?We'll try to do that but could you please explain,
what is the
difference in running stg2diag in linux and running
that utility using
MSDOS bootable floppy??
>Is the 75174 IC enabled By +5 to pins 4 and 12 (if itis 16 pin dip
>package)?YES, We already have connected the Active High Enable
signals of 75174
(pins 4 & 12) to Vcc=+5V
>Now after the IC you should have 8 wires to eachencoder. For me
>there are 3 separate shielded twisted pairs for theencoder outputs
>and +5 and a separate ground. The shields for thetwisted pair are
>hooked to star ground near the computer but LEFTUNHOOKED at
>the encoder end 2 meters or so away.Yes We have 8 wires after 75174 but all the wires run
in a single 13 core sheilded cable whose one end near
pc side is connected to Earth+Ground.
What is star ground?
>Can you get a scope to measure the signals? ChannelsA+, B+, and I+
> should be high and A-,B-, and I- low or vice versarelative to >ground.
>I still use a 1 meter ribbon cable in the control boxto go from a
>breakoutuses twisted
>board to the card. It is a special ribbon cable that
>pairs.Yes we measured the signals using osciloscope and have
>What do you use?
found that differential signals are always opposite to
each other.
We too have a ribbon cable which is one meter in
length but is simple one (found mostly in computers to
connect hard drives)
>What model of encoder are you using? What is thecount per revolution?
>How many rpm do you want to turn it?tried changing it?
>What is the base address of your stg card? Have you
>How are your other card dip switches set?The X and Y axis Drives have 200 lines encoders. Index
is working
The Z axis has 250 lines encoders. (Z axis encoder was
damage so we had fitted another encoder.) Index isnt
working alignment is out. but we'll fix it.
We dont know how many RPM should we run it at?
Base address of our STG is 0x200 and we didnt try to
change it.
Can changing this address may affect counter stucking
problem?
the DIP switch have default configuration:
Analog input range J2 = +/-10V
DAC latch on interrupt J3 = latch on interrupt setting
Watchdog J5 = Unlatched
Watchdog timeout slection = 333 msec
Source for CLK2 J7 = OSC/2
Jon you wrote:
>My servo amps have LC filters on the output, so thatno more than 1
>Volt of theservo amp. What
>100 KHz chopping waveform is allowed to escape the
>brand ofask if the output
>servo amp is used in this machine? I don't have to
>is filtered, itoutput filter may
>almost certainly is not. Unfortunately, adding an
>not be easy,would want to put
>at least without retuning the servo amp. But, you
>inductors ofeach motor output
>probably several hundred microHenries in series with
>lead.5 uF to the DC
>from the amplifier, and then a capacitor of perhaps
>power supplychopping
>ground from each motor wire. Without knowing the PWM
>frequency andspecific about this.
>the motor current, it is hard for me to be more
We are using servoamps are from WestAmp.
Peak current : +/-22Amp (for 500 msec)
peak voltage : +/-100VDC
Continous currnt +/-10 Amp
Continous voltage +/-92VDC
Switch frequency (constant) : 5Khz
Frequncy responce : 500 Hz minmium
Signal Input voltage : +/-10 V(typ) +/-50V Max
And we are not sure about the presence of LC circuit
in the drive.
>One possibility is to changecable shield is
>the wiring location of the encoder signals. If the
>grounded at both ends, thisgrounded only at
>is incorrect practice. The encoder cable should be
>the STG card end.counterproductive, you may do
>Using an external power supply may be
>better with theproblem when the
>internal power source from the STG card.
>Especially since the stg2diag ALSO shows the same
>servo amps aresoftware will
>on, EMC is not to blame. And, in fact, nobody else's
>run, either.No the encoder cable sheild isnt grounded at both
>Jon
ends.The encoder cable is grounded only at our
breakout board and from there it goes to STG-II via
ribbon cable.
We were using STG-II supply to power encoders but
since we used 75174
we observed the Voltage droped to 4.3V. so we now are
using external
+5V PSU.
Please comment
best regards
Babar
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Discussion Thread
lti_cnc
2002-08-28 06:50:42 UTC
Position counter stop updating....
Jon Elson
2002-08-28 10:09:47 UTC
Re: [CAD_CAM_EDM_DRO] Position counter stop updating....
riet91
2002-08-29 21:30:22 UTC
Re: Position counter stop updating....
Jon Elson
2002-08-30 10:54:54 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....
Babar
2002-09-02 04:28:15 UTC
Re: Position counter stop updating....
Jon Elson
2002-09-02 15:11:56 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....
Babar
2002-09-04 08:39:00 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....
Country Bubba
2002-09-04 13:32:20 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....
Babar
2002-09-13 04:21:42 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....Still there....
Les Watts
2002-09-13 07:17:04 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....Still there....
Jon Elson
2002-09-13 16:40:38 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....Still there....
Babar
2002-09-14 05:05:59 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....Still there....
Les Watts
2002-09-14 16:17:30 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....Still there....
Jon Elson
2002-09-14 21:47:47 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....Still there....
Jon Elson
2002-09-14 22:14:38 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....Still there....
Jon Elson
2002-09-17 10:18:34 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....Still there....
Babar
2002-09-19 02:24:52 UTC
Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....Still there....