Endstop connections on RAMPS 1.4 board

[iras]

Just bought a used Prusa i3 printer with a RAMPS 1.4 board (that might be redundant, not entirely sure). It checks out OK, although I need to do some cleanup and calibration.

Looking at the endstop connections on the board, there seem to be seven possible connection positions. Let's number them 1 though 7, with 1 nearest the power/heater connections side of the board.

There seem to be two positions for each axis if I'm understanding: X X' Y Y' Z Z' and ?.

The endstops, which DO work, are connected at locations 2, 3 and 5, which I believe are X', Y and Z.

Question: What's the difference between X and X' (or Y or Z for that matter)?

Question: What's the 7th position for?

Thanks.

[printbus]

The "seventh" row consisting of four pins is for an I2C data connection, not an endstop. There are six endstop connections. Each axis can have an endstop at the min travel and/or at the max travel. Most use just the min travel endstop, but a printer can be configured to use either or both.

Board markings have been reported to vary, depending on the source of the board. On my MakerFarm Prusa i3 RAMPS, the min travel endstops were connected to the rows of pins marked X-, Y-, and Z-, which I think were your positions 1, 3 and 5.

[iras]

Since the X endstop seems to be connected to the Max board location, and since things seem to be working, does that mean that the X direction of travel is inverted (direction of travel and endstop both opposite)?

When the printhead homes on the X axis, it goes furthest AWAY from the X Stepper.

[iras]

And you're correct (not that I doubted it) - the 7th row does have 4 pins. I should have seen that.

Thanks.

[printbus]

Since the X endstop seems to be connected to the Max board location, and since things seem to be working, does that mean that the X direction of travel is inverted (direction of travel and endstop both opposite)?

When the printhead homes on the X axis, it goes furthest AWAY from the X Stepper.

What does the Y axis do in homing? Home is typically in either the right rear or the front left corner of the print bed.

[iras]

Home is the front right corner. After some investigation, I have confirmed that the X-Axis limit switch on the right is used for the X-Max connection. Settings in firmware have the X-Axis inverted, and I've discovered (new to me, you guys probably knew this) that Repetier-Host needs to be told about this. Once I told it, everything fell into place and all is well. It even makes sense. Thanks,