Convert from Anilam Crusader M to EMC 2

Getting ready to hook up the 7i77 analog output into my servo drives. From the manual:

"The 7I77 provides six channels of +-10V analog servo interface on connector TB5.
Minimum load resistance is 2K Ohms."

if I measure resistance across the drive's analog input, I get resistance of about 260 ohms. Does this mean I need to add a resistor in series to bring the resistance up to greater than 2000 Ohms?

This sounds really wrong. Do you have the drive specifications or at least part number?

Also the input resistance may possibly read low when the drive is unpowered
(since the inputs may have clamp diodes to +-15V or something)

Connecting a 1.5V battery when the drive is enabled and measuring the current with a series mA meter may be a more realistic measurement of input impedance

Peter, thanks. I did as you suggested and input impedance is much higher than measured with my DMM measuring resistance.

For any future readers:
I needed to un-wire my drive enable connection to the 7i77 controlled by linux cnc since connecting the battery resulted in an immediate following error which disabled the drive. I measured about .07 mA or 20k Ohms with the drive powered. Interestingly this current reading measured spiked much higher when the 7i77 disabled the drive.

I was able to jog the z-axis satisfactorily last night with a P gain of 30 and I and D at zero. I need to dive more in depth on tuning now, but so far, so good!

If it is a velocity drive I have a velocity tuning tutorial on tuning on my web site.

John

only picking up this thread now, and please ignore if this is of no use or overly obvious:
my bridgport was an anilam crusader and fitted with a montec card.

I have had the green and red cards over the years.

Not sure wha tit is but these older card have a tendancey to blow the power tansistors. one can replace them and tbf that is what I generally do(rs sell the parts).
norwin say they changed the boards because the boards tended to blow, and the designated replacment transistors have a lessor spec then the originally design spec.
that being said, my mill has been stable for two years now.

fit independant servo drives enable lines on each servor drive card. When the transistors go U/S, they can go short cct and those axis flippin MOVE!!!!

I have the norwin setup pfd if you need a copy, pm me. it is important to get that servo drive card stable before PID tunning in software.
looking at your P and D values suggest things are ok, they are simular to mine.

Graydog, thanks.

I agree that getting the drives stable is an important first step.

Here is what I did:

1. open the following error way up to allow large error without aborting.
2. Test PID at zero gains for one axis at a time
3. Adjust the balance pots on my drives to minimize drift.

In my case, if the drift was in the "positive" direction, I would turn X-axis CCW, Y-axis CW, Z-axis CCW

At this point, using only P-gain, performance seemed decent, with some significant error during accel and decel

After that, I followed the advice here: wiki.linuxcnc.org/cgi-bin/wiki.pl?Gantry...Pulse_Generator_Mesa

and set my FF1 parameter to 1, and kept only the P-gain. following error was less than .0005" on each axis individually which seemed to me that was probably as good as I could hope for given the encoder resolution.

After decreasing the allowable following error to .002", and not running successfully, I increased it back to .005" and ran a test engraving successfully. My guess is that increased error is due to small backlash when changing direction.

In any case, I believe that observed performance is likely "better than new" compared to the original control, and I am a happy customer!

Thanks.