Mesa 5i25 & 7i76 to GE Af-300 VFD?

07 Feb 2017 03:50 #87434 by panchula
I'm updating my Boss 5 and have run into trouble getting the 7i76 and the AF-300 interfaced. The speed control via the potentiometer replacement on the 7i76 was straight forward. Getting the enable and direction from the 7i76 to the AF-300 is unclear. I did find a reference to using a SPDT relay and have procured one. If I have properly wire it in has me at a standstill. I think I have but could use a sanity check. Here's the link and excerpt.

The pertinent passage from the above link is:
The VFD gives us:

CM - Digital input common
FWD - Forward command (24V sourcing)
REV - Reverse command (24V sourcing)
There is no explicit enable or start pin (that I could identify).

The operational mode is described in the manual as:
- Forward operation with FWD-CM connected and deceleration to stop when opened.
- Reverse operation with REV-CM connected and deceleration to stop when opened.
- No operation if both FWD-CM and REV-CM are connected.

How does this apply to the 7i76 pins (ENA-, ENA+, DIR-, DIR+)? Do I have to repurpose them as a FWD-, FWD+, REV-, REV+, and write something different in the HAL configuration (I have not yet dug into manual hal configurations, though clearly I will have to soon). Or am I just missing an obvious hookup option here?


Unfortunately the 7I76 spindle interface only supports ENA/DIR type control inputs.
Many drives have this option but it appears that your drive does not.

It may be the the easiest way to control the VFD with minimum added hardware
would be to add a SPDT relay driven by the direction signal:

ENA- ---> GND

RELAY COIL+ ---> +24V
DIR- ---> GND

Do I read this as the ENA+ 24v from field power being the source that is passed to the VFD via the relay's NC and NC contacts?

I just want to be sure I have it right and don't smoke anything when it gets it's first power.

08 Feb 2017 12:25 #87529 by andypugh
I have a feeling that, in your scheme, ENA- should go to CM not GND.
09 Feb 2017 02:23 - 09 Feb 2017 16:20 #87630 by Benb
You need two relays, one relay for forward action and the second relay for reverse. one relay for 'enable' second for direction See attached revised diagram to help you wire this part of you project./
Last Edit: 09 Feb 2017 16:20 by Benb.
09 Feb 2017 11:04 #87647 by andypugh

Benb wrote: You need two relays, one relay for forward action and the second relay for reverse. See attached diagram to help you wire this part of you project.

I think that his scheme with one relay will work.

His plan seems to be to use the 7i76 "enable" to turn on forward or reverse, and uses the relay to select which terminals the "enable" output is connected to.

However, it is probably worth testing to see what the drive does if both FWD and REV connections are made at the same time. If this results in reverse running, then no relay will be needed.
18 Feb 2017 04:19 #88156 by panchula
OK, I've made progress. All the axes move. The TB4 analog output seems to be working M3 S2000 gives me 10.13V and M3 S1000 gives me 5.04V. I still can't get the spindle to turn on.

I have it wired as mentioned above.

Here are the the voltages I'm seeing:
Pin Off M3 M4
+A1 28.42 28.17 28.11 Coil Pos
-A2 28.09 27.84 27.81 Coil Neg
11 0.011 0.013 27.44 Relay COM
12 0.014 0.016 27.43 Relay NC
14 0.014 0.016 27.42 Relay NO

Interestingly, the VFD responds with a frequency displayed on it's front panel only with the M4 command. Close, but no cigar.

Any ideas on where to go from here?

18 Feb 2017 17:59 #88176 by PCW
Before you connect _anything_ to the 7I76 you should verify
that you can control the spindle drive with hard wired inputs or
mechanical switches.
18 Feb 2017 18:46 #88179 by tommylight
Short the fwd pin to the CM pin, test in Linuxcnc if you can control the speed. Since you say only m4 will activate the pindle, you do not have it set up properly. It has to be set as a spjndle in hal to be able to control the speed, mist and flood only have a pin without the speed part.
I think you can wire the ena+ to the fwd pin and ena- to the CM pin, or the other way around without a relay if you need only one direction.
18 Feb 2017 22:07 - 18 Feb 2017 22:47 #88192 by bevins
There is another pin you need with that drive. I thinks it cmw or something, i will check later when i get to my shop.

The other pin needs to be tied to cm and it needs to be n/c and open to stop. So use that fwd when spindle gets enabled then use the other signal to pulse a stop. I am pretty sure the fwd is a pulse also. Will check later tonight.

This is not true, on mine there is another pin,

So if you are using 0-10 spindleout connect to pins 11 and 12 observing plarity. I would test with batteries say two aaa give you 33 percent of you max speed.

But you have to close 24v to FWD. if you want reverse, then close 24v to REV.

It seems you have to check the setup because you can change the requirements of x1-9

That should make it work. I didnt use ena. I connected a relay to motion.spindle-on and closed my fwd.
Easy, one relay for fwd and one for rev. No fuss no muss.
Last Edit: 18 Feb 2017 22:47 by bevins.
19 Feb 2017 04:16 #88230 by Benb
Here are two solutions in schematic format (see attached), the one relay solution is the solution that was suggested in the previous replies..

The one relay solution is simple, sweet and the list costly but if something goes wrong with the VDF you might end up damaging your mesa card. The two relays solution keeps Mesa and the VDF power supplies separated so one misshape with one card will not affect the other, the LED's in the relays will help you with troubleshooting in the future and if enable works backward you can reverse the logic.

So now you have worded solutions by previous members that replied to your inquiry and visual solution.

Good luck
20 Feb 2017 02:48 #88316 by panchula
Many thanks to all who replied. My additional relays arrived, and I went with the two relay solution keeping the VFD and 7i76 voltages separated. I now have the rest of the machine to sort out.

Again, thank you all.

Moderators: PCWjmelson
Time to create page: 0.218 seconds
Powered by Kunena Forum