How to manage the coordinate table through your program?

Question

Programming

There is a coordinate table. You need to control the coordinate table through your program (not through Mach3). All that is known is the pinout of the LPT cable, which connects the LPT port of the computer to the LPT port of the control unit for this table:
2-X_DIR,
3-X_STEP,
4-Y_DIR,
5-Y_STEP.
STEP-DIR protocol. Tried to get the values ​​that Mach3 writes to LPT via PortMon. PortMon is silent. I tried the old dos program lpt_test. Nothing too. Tried to emulate Up, Down, Left and Right keystrokes via SendMessage/PostMessage/keybd_event in my program. The result is null. The coordinate table is needed to test the manipulator. If anyone has already done this, please respond, share your experience.

Answer 1

1. STEP / DIR - not quite a "protocol" - the logic is simple: the DIR signal sets the direction of movement (for example, with DIR = 0, the table moves forward, respectively, with DIR = 1 - back), STEP - step pulse (one pulse = one step of the drive, i.e. to move by a certain amount, the corresponding number of STEP pulses must be applied). Well, the port of the control unit with the LPT has in common only the same connector and the logical level of the signal - the pin assignment is completely different, which is why lpt_test does not produce anything.
2. In order for Mach3 to output something in LPT, you need to configure it in accordance with your wiring: look in the settings menu for the tab with the "signal-pin port" correspondence table and put the necessary numbers there.
3. Manage from some of my programs - I don’t know here: it seems to me that you need to write your own driver for this ...

Answer 2

We did something similar - there was a kind of coordinate machine with stepper motors - which was controlled via LPT by an inconvenient program - K-cam, it seems. We connected an oscilloscope (we didn’t know about the LPT 3D Hard Analyzer), we looked at what goes where when we press the buttons in the program.
Then we compiled a list of commands and wrote our own interpreter in BC++, everything worked on WinXP just through the LPT port - I don’t remember exactly - but it seems that they used the same inpout32.dll - they didn’t write their driver 100%.