On Tue, 19 Nov 2024, Viesturs L?cis wrote:
Date: Tue, 19 Nov 2024 22:24:18 +0200
From: "[UTF-8] Viesturs L?cis" <viesturs.la...@gmail.com>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Subject: Re: [Emc-users] 2 questions (probably) for PCW
otrd., 2024. g. 19. nov., plkst. 19:45 ?? lietot??js Peter Wallace
(<p...@mesanet.com>) rakst??ja:
I would check the 7I36 output voltage when disconnected from the VFD. If that
seems ok, it may be a VFD EMI or grounding issue. This might require a line
filter on the VFD, a common mode choke on the VFD wired going to the motor, or
possibly a common mode coke on the analog signal/gnd wires going to the drive
I have attached a screenshot from VFD's manual that shows control
terminal wiring. Those are "active low" inputs.
I have connected terminal-11 to "minus" of 7i37 outputs and
terminal-14 and terminal-15 to "plus" of each of 7i37 outputs. And
terminal-4 and terminal-5 with separate cable to analog output pins.
Is there any chance it could be caused by config? I had it working
previously in this machine, but I did change to better pc as the
initial was quite old and the realtime performance on bookworm was
bad.
Ok, I will check with disconnected cable.
The given a fixed PWM value (no feedback) The only way I can see
getting a varying analog output would be if the PWM frequency was
way too low.
Is there a complete specification of the C signal protocol?
That link has the most detailed description I have found so far. I
could ask Alciera if there is more available...
I did a trace of C channel pattern with regards to A and B channel.
There are 6 different patterns that repeat 4 times on full revolution
of motor shaft. Those are 8 pole motors, 4 electrical revolutions, so
those 4 repetitions explain themselves. I have 24 csv files from
HalScope that show pattern of A, B and C signals. The thing is that
sometimes C channel can have 2x pulse frequency compared to A or B -
in some patterns there is separate pulse on both rising and falling
edge of A pulse. 6 different patterns sound exactly like 6 different
stages of Hall sensor signal. I do not necessarily need index pulse, I
have not used it so far (although homing on index might be a good
idea), rotor homing for bldc component is the main concern here.
otrd., 2024. g. 19. nov., plkst. 20:33 ?? lietot??js gene heskett
(<ghesk...@shentel.net>) rakst??ja:
The first thing I'd look for is a ground loop.
Ok, thank you, I will try to check.
otrd., 2024. g. 19. nov., plkst. 21:19 ?? lietot??js andrew beck
(<andrewbeck0...@gmail.com>) rakst??ja:
But I thought I would just try one of peters ency cards
It's a encoder splitter that takes in one channel and makes 2 out.
I did not know about existence of such a tool. The fact that I do not
see it available from any european reseller is just a minor
inconvenience. The actual issue is that I have 2 machines with total
of 7 drives (and there is one more of my previous retrofits that has
at least 1 servodrive not working so I would like to replace that as
well). Only 2 of them are used for actually driving the motor, 5 of
them are are replaced by 8i20 and now are used solely for chewing and
digesting the C channel pattern and giving out proper encoder signal
in a form of A + B + index. I use the index for bldc component only.
Fortunately for me the encoder output died on a drive that moves C
axis motor (at the moment it is optional and does not cause a lot of
inconvenience as I am now finishing toolchange and remap of M6
command). If it was _any_ other of those drives, that would be trouble
to say the least, so that is why I am asking about chances to read and
interpret C axis pattern in LinuxCNC.
Viesturs
Peter Wallace
Mesa Electronics
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