ESS MB3 Analog to VFD LED on but no voltage

Setup - ESS, MB3, Mach3 R3.043.062

I have configured Mach3 and when I issue an M3 with a speed the LED for the analog signal on the MB3 lights up. Slower speed, dimmer light. Higher speed brighter light. Should be OK but there is no voltage to the connected wires. I've replaced wires, changed meters, reversed leads, still no voltage.

Anything I'm missing?

Hi,
you need to confirm with the circuit diagram of the MB3, but its primarily for a VFD. The VFD is supposed to supply a steady DC voltage, usually 10VDC
and the MB3 'modulates' that voltage to anywhere between 0V and 10 V. The PMW output pin does not provide any voltage unless the MB3 is provide with it in the first place.

Craig

In my other conversions, the ESS and MB3 boards are set up before connecting the VFD to confirm the AG/AO circuit is configured correctly in Mach. Once I get the correct voltages I connect the VFD and calibrate the spindle speeds. Has this changed in the past 4 months?

Hi,
not to my knowledge. The MB3, like almost all BoBs 'processes' the voltage supplied to it from the VFD.

The breakout board has its own power supply. The VFD has its own power supply derived from the incoming 230VAC. What is to say that the 0V points of both power
supplies have to agree with each other? They may differ by a few or even tens of volts. The BoB is producing 5V say for a half speed spindle, but because of the 0V
clash the VFD sees 8V and goes at 80% of speed. All wrong because the 0V of each device is not the same.

So, at the very least the 0V of the BoB must be connected to the 0V of the VFD. Depending on the VFD they may call it DCom or something but it establishes that
both 0V's are the same in both devices.

Do you have or have you supplied a 10VDC source to the BoB? If not, then how is it you expect the output pin to produce a PMW or percentage of the 10VDC?
For this reason the VFD manufacturers provide the 10VDC at a terminal on the VFD, where it is connected to a BoB that 'processes' that voltage and returns a percentage
of it back to the VFD.

In total you need three wires from the VFD to BoB. One for the 10VDC 'supply', another for the common return which establishes the 0V of the BoB and the 0V of the VFD as the same,
and the last wire returns a percentage of the 'supply', 0V-10V, back to the VFD.

Craig

From the MB3 Manual and how I set up the last 4 machines I converted.

"New! “AnaSpeed2”is a 0-10V precise analog output circuit has been implemented. This small circuit island is electrical isolated from the rest of the board, but it forms itself as part of VFD input circuit which receives PWM signal from ESS by using light. It also has on board isolated DC2DC module which able to supply 0-10V to VFD continuously. "

The schematic further down shows the AG being directly connected to the VFD common and the AO connected directly to the VFD Analog In. No mention of supplying a power source as the 2 DC2DC converters onboard the MB3 are for the 5VDC inputs if needed and the 10VDC used in the Anaspeed circuit connected to the MB3 AO pin. This particular Yaskawa VFD was using a rheostat connected to the VFD's 15VDC output for analog references with a ground and the output of the rheostat connected to the Master Speed Frequency Reference which only registers 0-10VDC.

So I'm not quite sure where I would get a 10VDC connected into the the circuit with only 2 wires connecting the MB3 analog output to the VFD. Of course there are 4 other wires, 2 each for forward start and reverse start.
Where would this 10VDC wire be input to the VFD and the MB3?

Hi,
well maybe the MB3 is different to all the other BoBs out there. If what you describe is true, that is that the MB3 produces its own current, and its not doing so then its
faulty.

Craig

Here is a schematic CNCRoom published on it's site to connect a Huanyang VFD to a ESS/MB3.

Attachment 489088

Somehow, I have to get this running by tomorrow afternoon as their production schedule demands the machine be in service. What outputs do BOB's without the Anaspeed circuit output a controllable 0-10VDC to the inverter?

Hi,
I have attached a pic of the somewhat simplified PWM circuit. Note that the PWM really only swtiches the input voltage (from the VFD) to 0v, on and off a bit
like a light dimmer. The resistor and capacitor form a low pass filter. This is too crude to be considered a good circuit. I made my own breakout board and its has a more
sophisticated circuit that results is very nicely linear output voltage (within 2%) with only a few millivolts of ripple.

Have you considered putting a modest resistance, say 1kOhm from the 10VDC output of the VFD to the PWM output terminal of the MB3, a sort of pull-up resistor?
If you have to get it going on a time limit would it not hurt to try? It may not be perfect but it would get you going.

Craig

Hi,
Ok, from your description the MB3 must be faulty, the PWM output circuit.

Why don't you use another output? The ESS has plenty of outputs, any which could be assigned to the ESS PWM signal. Then a handful of electronic components to turn that into
a 0-10V analog signal. If your on a schedule???

Craig

@fidelma. I'm having the same issue it's driving me nuts! Not sure if its also related but don't see the state of any of the on-board relays change when I set the outputs. Again the lights of the board do turn on but NO and NC outputs don't... I'm suspecting that part of the MB3 is blown, but CNC Room seem to be on holiday until the end of April.