[BZee]

Hi, wondering if anyone knows anything beyond just connecting wires, or switching it on to see if it works?

Mach3 instruction video for a 3 axis drive project involves six pins, 2 - 7, three for motor pulse and three for direction. Direction seems relatively straight forward, you're either going one way or another and so signal strenght only has to indicate a change, but pulse has attached to it feed rate. Anyone know how Mach3 signalls this using the one wire, and is the signal constant or does it also pulse?

P.S. not just idle curiosity, I'm getting no change on direction on the DIR signals, and my X when compared to Y runs harder, both are set the same under dips and Mach3, then there's my Z, or rather there's not.

Wire swapping says all three motors and drivers function, leaving the PC connection (LPT1) or the BoB. I'd like to be able to establish which (if possible) by using a metre on the LPT1 input to the BoB and then the BoB's output if the former is ok.

Anyone who's been in a similar position, it would be great to hear how you resolved, Thanks, Zee.

[Mzones]

Simply the printer port is 17 individual TTL logic gates
There is only two pin states on the printer port, either its on. or it is off.(High or Low)
One on and one off equals one cycle. On the step pin, the number of cycles
determines distance of travel, the frequency of these cycles determines
the speed.

The direction pin is either High or Low.

[john-100]

Hi BZee

while its not perfect this diagram should give you an idea of how the original printer port worked


Attachment 221008


for instance with the parallel printer port address set to 0x378 (hexadecimal , base 16 )

when the first 10 address lines from the uProcessor are set to 378
this address is decoded and combined with the I/O write signal to clock the
8 bit data into the D-type DATA latch thats connected to port output pins 2 to 9


the decoded address 379 is combined with the I/O read signal to enable
a 74244 tri-state buffer used as the STATUS input port
this connects the 5 input pins10 to 13 & 15 to the uP data bus (D0 to D5)

decoded address 37A and I/O write signals are used to clock data into a second D type
used as the CONTROL port connected to the printer port output pins (D type 1 , 14 , 16 & 17)


later printer ports have bi-directional DATA latches that can be used as inputs or outputs
connected to pins 2 to 9 and is combined into the south bridge or super I/O chip
on the mother board or one lsi chip on an adaptor card


John

PS

from what I've read
not all PCI adaptor cards can be set to the first 3 addresses (0x278 , 0x378 or 0x3BC )
required by some old DOS based programs
not sure if this applies to Mach 3
but it could explain why some printer port adaptors fail to work

[dkowalcz]

Direction pins are either 5V and 0V corresponding to each direction (you can specify in the setup which corresponds to + and -).

Step pins sit at one voltage and briefly "pulse" to the other before switching back. When this happens, the motor takes one "step" of rotation - just imagine pressing a button to go one "bump" of movement only. These are timed to produce coordinated motion and acceleration - imagine tapping these same buttons in rhythm like the old Etch-a-Sketch toy and you've got the idea.

The step pulse is too fast to see with an ordinary voltmeter.

Some parallel ports only put out 3.3V for high instead of 5V, which is a problem for certain breakout boards depending on their electronics.

Just fake the inputs to the BOB with some wires and a 5V supply; you'll immediately find out whether the issue is downstream (motors, drives, BOB) or upstream (port and configuration).

Good luck!