7i77 testers wanted

PCW wrote:

A few observations:

1. Why are you not using the drive enable outputs of the 7I77? That is their intended purpose. They have the advantage that they are "floating" switches so can be used with active high and active low enables. They have the additional advantage that they can use a separate supply so you can use them with enable inputs that have a different voltage requirement than the field I/O (which is normally 12 or 24VDC)

2. HM2 encoder "Counter mode" which is an up/down count mode
as opposed to the normal reversable quadrature mode is not suitable
for MPGs so this should be set false

1. I am not using them because it was negligibly easier to use an x-enable function with the existing circuitry. If it's going to make things more complicated, I can easily switch to those drive enable pins. I'll give that a shot. Did you have any thoughts on the positive feedback phenomenon?

2. I'm sorry but how do you know it is in counter mode and how would I change that?

Thank you.

If the existing enables work I would not bother at this point but it does add some design contraints that may be a problem later on (you need to have active high enables on your drives that will work with the common field voltage for all isolated I/O)

To fix a positive feedback problem (and assuming your encoders are counting in the proper directions, if the encoder count backwares, reversing the sign of the encoder scale (or swapping encoder leads) will fix the problem) you need to reverse the output. I _think_ this is done by changing the sign on the appropriate maxoutput variable (But Andy should be consulted on this as its not in the hm2 manual yet)

as far as counter mode goes, your example hal file had set counter mode true here:
setp hm2_5i25.0.encoder.05.counter-mode true
(which you do not want)

PCW wrote:

If the existing enables work I would not bother at this point but it does add some design contraints that may be a problem later on (you need to have active high enables on your drives that will work with the common field voltage for all isolated I/O)

The existing enables don't work. The relay that enables the axis drives do work with a field I/O level signal but the 7i77 isn't turning them on when it should.

PCW wrote:

to fix a positive feedback problem (and assuming your encoders are counting in the proper directions) you need to reverse the output. I _think_ this is done by changing the sign on the appropriate maxoutput variable (But Andy should be consulted on this as its not in the hm2 manual yet)

as far as counter mode goes, your example hal file had set counter mode true here:
setp hm2_5i25.0.encoder.05.counter-mode true
(which you do not want)

It appears that you're right about reversing the output. I physically reversed the connections on the amplfier input signal and I don't seem to be getting the positive feedback anymore. Scale may be the one that needs to get negated.

Thank you for the counter mode assistance.

Yes, changing the sign on maxscale should reverse the output polarity

Why do the enable outputs not work? Normally drive enables require either a pulldown to ground or a pullup to some voltage to enable. The 7I77 enable outputs can do either of these. (within their 100V 50 mA limits)

PCW wrote:

Yes, changing the sign on maxscale should reverse the output polarity

Why do the enable outputs not work? Normally drive enables require either a pulldown to ground or a pullup to some voltage to enable. The 7I77 enable outputs can do either of these. (within their 100V 50 mA limits)

I meant that the current configuration, where I'm trying to use X-enable, Y-enable, and Z-enable output pins offered as a choice in PNCConf. The 7i77 servo enable circuits do work, I believe. I haven't tested them with the servos yet but they work well for the spindle. I need to connect them up such that they will supply a 24V field I/O signal to the servo amplifier enable relays.

Oh OK, just wanted to mention that they should pretty much always work for enables (other than direct relay driving of more than 50 ma)

BTW something must be setting the analog enables on or the analog outs will be at 0V

andypugh wrote:

maxvdh wrote:

net estop-out hm2_5i25.0.7i77.0.0.output-00
net xenable hm2_5i25.0.7i77.0.0.output-03

Well, these are half of it, defining signals and where they need to go to. What I don't see in the lines you have pasted is where the signals come from.
I would rather expect to see, for example
net estop-out halui.estop.is-activated
because estop-out is just a signal name, and it has no meaning to LinuxCNC. halui.estop.is-activated, however, is an output pin driven by LinuxCNC.
The same is true for xenable, I would expect it to be netted to axis.0.amp-enable-out

(Yes, i do know most of these pin names off by heart, but they are all listed in the docs for example:
www.linuxcnc.org/docview/html/gui/halui.html
www.linuxcnc.org/docview/html/man/man9/motion.9.html
Knowing where to look for each one is a bit more difficult)

net jog-incr-a => jogincr.sel0
net jog-incr-b => jogincr.sel1
net jog-incr-c => jogincr.sel2
net jog-incr-d => jogincr.sel3

Here we have the reverse problem, I don't see where jog-incr-a etc are driven from. I would expect them to be wired to gpio and from there to the jog-speed selector switch.

Turns out pin misspelling was the issue with this one. It is "x-enable" that is netted to axis.0.amp-enable-out. HAL file said "xenable", no dash. That's one problem solved. THANKS!

Still wondering about the lack of positive DAC output for the spindle when the spindle runs in reverse, as was discussed in that thread I mentioned. Is there something I can do to properly configure this in PWM "mode 1"?

The 7I77 does not have any PWM modes. If your VFD cannot be configured for +-10V operation, the ABS component must be inserted to make the spindle speed request always positive

Thanks!