Originally Posted by
Doddy
Depends entirely on the pin mapping on the BOB - not all are the same.
OP: Let's start from the beginning - you say nothing work. You suggest that you can measure voltage?, so let's concentrate on one signal and see where that takes us.
It would be useful for an image of the input pins, as well.
With all plugged in and ready.
1) Within Mach, can you cause the DROs to change by using the cursor right key?, if not, can you do so with a "G0 X10" on the MDI? If so continue...
2) Within Mach, can you cause the DROs to change by using the cursor left key?, if no, can you do so with a "G0 X0" on the MDI?, If so continue...
3) Connect a meter to the BOB pin for X Axis Direction pin (whatever it's called - unfortunately I can only guess without a clear image of the BOB, but pin 17 if your settings are correct). Connect red lead to X Axis Direction, black lead to 0V. (The X Axis being the screw terminal around the periphery of the BOB).
4) After (2) above, either press right-arrow to increase the DRO (X) value, or enter MDI "G0 X10". Measure and report here the voltage measured at X Axis Direction output.
5) After (4) above, either press left-arrow to decrease the DRO (X) value, or enter MDI "GO X0". Measure and report here the voltage at the X Axis Direction output.
(4) should measure either 5V, or 0V, whereas (5) should measure the opposite. You're basically changing the direction signal from one way to the other.
The purpose of this is to verify a number of things. That there is at least basic signalling from the PC to the BOB. That this is compatible with the BOB (e.g. if the motherboard is using RS232-5V signalling and not e.g. 3.3V), that the cabling is good and that the motherboard printer port is active and working. If you can't get this far then we can start isolating the problem(s).
If you can confirm the expected behaviour at (4) and (5), if you can repeat for the Y axis (pin 8), and Z axis (pin 16) (amending the MDI commands of course, and/or different cursor/pageup/down keys).
From the behaviour that you describe - I'd expect that the voltages measured at the (17), (8) and (16) remain constant throughout. This would certainly describe a fault with the interface from the PC to the BOB.
At this stage I'd really like a close up image of the BOB. The image above suggests a ribbon connected to the board, and another IDC header on the board, I can't see what the relationship with this is, but I'd like to understand if you can possibly try the following:-
6) Disconnect the parallel cable. Short the pin 17 on the DB25 parallel port on the BOB to ground. Measure the X Axis DIR output voltage and record here.
7) Short the pin 17 on the DB25 parallel port on the BOB to +5V. Measure the X Axis DIR output voltage and record here.
As before, between (6) and (7) you should see the X DIR output set to either +5V or 0V (I'm guessing that this will take the same sense as the voltage on the DB25 pin 17 input). If not, then the BOB is not behaving as expected.
8) If not as expected, without shorting any pin on the connector, measure the voltage on pin 17 of the parallel port output pin on the printer cable, plugged into the PC and disconnected from the BOB. Repeat (4) and (5) - again, we expect the measured voltage to change between 0V and 5V.
9) If not as expected, move the measurement to the parallel port on the computer. Pin 17 to PC ground, and repeat. If this doesn't change between 0V and 5V.
... and if that doesn't resolve anything, buy my wife and I air tickets to Brisbane for, say 2 weeks, and I'll bring my meter :)
Last Activity: 13-02-2020
1) Within Mach, can you cause the DROs to change by using the cursor right key?, if not, can you do so with a "G0 X10" on the MDI?
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