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Hu Gemox,A plasma cutter generates a huge amount of electrical noise, so all signals should be galvanically isolated.For this reason, I would not recommend the Mesa 7i97. Instead, I would use a 7i83 for the analog outputs, since it provides galvanic isolation from the rest of the control system.To determine the complete hardware configuration, the machine’s existing electrical schematics would need to be reviewed.A THCAD2, or an equivalent interface, is necessary to measure the plasma arc voltage. This voltage measurement is used by the torch height control to maintain the correct distance between the torch and the plate.I would not recommend using a stepper motor for the Z axis, as it may not be able to achieve the required speed.How are you planning to generate the G-code?

Logthor wrote:

this would work, right? 

Yes, this is a very similar circuit to the one used in BOB and will work identically.
The difference is that the power supply for this circuit should be not used for anything else, that BOB does not provide.
Voltage is a potential difference and is measured between two points.
The same wire, it may be 12V to the second pole of the power supply, but hundreds of volts to machine chassis.

GH, I don't get the email notifications here, and I have to remember to check

store.mesanet.com/index.php?route=produc...oduct&product_id=399
Click on "specification" then Download Support Software

Did you download this through the pcnconfig or the browser?

I would think something like this would work, right? It has a PC817C, so I figure it is used to optically isolate the two circuits. What has me slightly concerned is that the listing (and many others) don't mention the fact that they are optically isolated (does this mean that it isn't?).

I see what you mean now about it not being properly isolated. I'll buy a cheap board off of amazon. In the mean time though, I just want to make sure I know how to set it up in general. I just want to know why I'm not getting anything out of it when I issue a s command.

tuxcnc wrote:

... but 12-24V is also used to power the home, estop and probe inputs on the opposite side of the board.

So no, BOB is not properly isolated for this case.

tuxcnc wrote:

it is safer to use a separate cheap Chinese PWM->0-10V board and a separate small power supply.

You should really, really take his advice, and be very careful with wiring.

I don't have my KBIC attached. I just wanted to see if I could read a voltage of 7 at 1400rpm from the terminals of the bob before I even attach it to the KBIC. The KBIC is not isolated, but the BoB is supposedly.

You are looking at the wrong side of the problem, BOB is not the part with issues, KBIC is, so you must check and be sure the inputs on the KBIC are galvanically isolated from the rest of the board.
If they are not isolated, ... well i would throw it in the bin, but you can get some kind of isolation probably, or just use a relay to run it at full speed using the relay on the BOB should do, most probably.
This is something you do not play with.

Just tried a 7I95T (Rev. A) with

(MD5 checksum)

f1c9dff646bc7496e0883b3d0afbc05d  7i95t_1v3pkt.bin

And all works as expected with a GS10 VFD

PktUART pinout for this configuration is:



 

This is with 2.9.10 and Master =2.10Pre (as of a week or so ago)

I also checked:

26b79f7bdef81b79ab3299925886b118 7i95t_1pktv2d.bin

and it worked as well, though it uses the other 7I95T RS-485 connection

You can use 7i80hdt_sv12d.bin (for 3 7I33s)
 Just enable 4 encoders and 4 PWMgens and the
rest of the pins will revert to GPIO (for the 7I37s)
 

Yes, I'm seeing exactly the same issues you're describing.

Adding M5 to on_abort.ngc does indeed work well in this case, although, as you say, it only masks the problem.

Nevertheless, it won't hurt to leave M5 in permanently.

I tend to think it'll be fine as all I'm using the 24V is for my homing switches and powering the board to let me control the spindle.

Regarding how I go about controlling the spindle, I'm not sure about how to do it. I have attached my hal file below. When I measure the voltage between the pins circled in red I get 0.01 Volts (even after I've homed my axes and and sent it an m3 s500).


 

Logthor wrote:

I believe my BoB is optically isolated ( this is the link to it). 
 

I just measured it. The 5V and 12-24V voltages are isolated from each other, but 12-24V is also used to power the home, estop and probe inputs on the opposite side of the board. If there is a risk of applying high potential to the 12-24V power supply, it is safer to use a separate cheap Chinese PWM->0-10V board and a separate small power supply. As for the 0-7V range, it is probably enough to scale the spindle speed appropriately (for example, setp pwmgen.0.scale 2000 instead of 1400, i.e. 1400 rpm will be 70% of 10V)