[Joz]

Hi, wondering if you can help, I am new to CNC machining and Mach3.
I have wired up my CNC machine and started setting it up to run on Mach3.

The problem:
Mach3 will not register the limit switches or the E stop switches and the Stepper Motors will not turn.
If I hit an E stop or push a limit switch, the LED's in Mach3 on the diagnostics page do not light up.

The hardware I am using: (all from CNC4YOU.co.uk)
HG07 break out board
CW5045 Stepper Motor Drivers
60BYGH401-03 stepper motors
Windows XP on a dedicated PC


What I have done to try and get it to work:
Checked all wiring, reinstalled Mach3, checked parallel port driver. The steppers are receiving a voltage, and the limit switches and the
E Stops are on a Normally Closed circuit, which breaks when I push a switch and test it with a multimeter.
I have run driver test= system excellent.
Under Ports and Pins:
Port set up is on port 1, 0x378
Motor outputs for X,Y & Z are set up on what I believe be the correct pins, DirLow Active is enabled
Input signals are set to port 1, each limit switch and E stop has the correct pin number entered, active low is enabled for each.

Can anyone help? It's probably something dead simple but I at a loss to know what to do next.
Many thanks
Joz

[doorknob]

I would focus on the lack of communication between the breakout board and Mach3 first. Some things that you could check:

1) Is your 25-pin cable actually a "straight-through" cable, with all pins connected?

2) Do you have power connected to your breakout board? What voltage are you using, and what pins have you hooked it up to? Do you see +5 volts on the common line shared by your limit switches?

3) Measure the voltage between the Dir pin for one axis and ground (preferably at the parallel port connector, and then test it at the end of the cable) while you are jogging that axis in one direction or the other. You should see a 'high' (5 volt) reading when jogging in one direction and a 'low' (0 volt) reading when jogging in the other direction. If you only see about 3 volts instead of 5 volts, then your breakout board may handle it OK, but less than that may cause problems. If you don't see the voltage in one direction and no volts in the other direction, then the problem is likely within your parallel port or the parallel port driver or the Mach3 setup.

[Joz]

Thanks- I have checked through the things you have suggested.

1. The 25 parallel port cable is not a "straight through" cable as such, it wasn't long enough to reach so I bought an extension for it. From the breakout board, it consists of a female to male, a female to female adapter, and a male to male cable into the computer. I'm not sure if this is relevant but I guess it's worth mentioning.

2. There is power connected to the breakout board, 38V. The BOB can take between 7V and 55V. It is connected to the power pins on the BOB. If it's of interest/help, the PDF for the break out board is here
"Do you see +5 volts on the common line shared by your limit switches"- I'm seeing 4.25V when the limit switches are pushed (disconnected) and 0.01V when they are open.

3. I have measured the voltage between the Dir pin and ground for each axis. I measured it at the output terminals of the BOB (rather than at the parallel port connector as this is difficult to get to with the probes). The voltage measures a steady 4.62V whether the the stepper motor is stationary, or jogged either way.

[doorknob]

Thanks- I have checked through the things you have suggested.

1. The 25 parallel port cable is not a "straight through" cable as such, it wasn't long enough to reach so I bought an extension for it. From the breakout board, it consists of a female to male, a female to female adapter, and a male to male cable into the computer. I'm not sure if this is relevant but I guess it's worth mentioning.

The key thing to determine is whether each of the pins goes "straight through" electrical connectivity-wise from the parallel port side of the cable to the breakout board side of the cable.

For example, pin 1 of the cable on the parallel port side must be connected to pin 1 of the cable on the breakout board side, and not be connected to any other pin, pin 2 goes to pin 2, etc. (at least up to about pin 18).

3. I have measured the voltage between the Dir pin and ground for each axis. I measured it at the output terminals of the BOB (rather than at the parallel port connector as this is difficult to get to with the probes). The voltage measures a steady 4.62V whether the the stepper motor is stationary, or jogged either way.

Can you measure it at the pins of the cable on the side that attaches to the BOB (without the breakout board attached)?

The goal is to figure out whether your PC is sending the proper signal to the breakout board. Measuring the voltage at the output terminals of the BOB will not suffice.

[Joz]

Fixed! It was a faulty parallel port cable. I've replaced it and it's running ok now.
Thanks for the help.

[doorknob]

Glad to hear it...