Homing Switches & Routine

[suntravel]

Kind of stupid question maybe, but how do it work that the first axis stops reaching home when the sensors are wired in series ?

Regard

Uwe

[ShawnM]

Kind of stupid question maybe, but how do it work that the first axis stops reaching home when the sensors are wired in series ?

Regard

Uwe

Not quite sure what you mean. You can wire proximity switches in series to one Acorn input. Use 24 volts when doing this if the range is 6-36 volts on the sensor. To low of a voltage can cause problems.

[suntravel]

Well the loop will be closed after all switches are closed, so when the first switch is closed, how does the Acorn know the first axis is home and stops it moving ? On the systems I know each home and/or limit switch has its own input for each axis. You can send them home with one command, and each axis stops reaching home when its own switch with own input is triggert ...

[ShawnM]

Well the loop will be closed after all switches are closed, so when the first switch is closed, how does the Acorn know the first axis is home and stops it moving ? On the systems I know each home and/or limit switch has its own input for each axis. You can send them home with one command, and each axis stops reaching home when its own switch with own input is triggert ...

You have to use NC switches if you are wiring them in series. The Acorn homes one axis at a time. With all switches in series the loop is closed. When the first axis reaches home it opens the loop and stops that axis and homes it. Then it does the next axis and then the third (and 4th if you have one). You can set the order and direction it moves to seek the switches in the wizard. Normally open switches are wired in parallel if you are sharing an input.

[RJS100]

I had the same question when I started wiring these home switches. As Shawn mentioned "The Acorn homes one axis at a time. With all switches in series the loop is closed". What I did not realize is that immediately after Acorn homes a switch and opens the normally closed limit switch, Acorn moves the axis a millimeter or so in the opposite direction which closes that limit switch. Once the limit switch is closed, Acorn moves on to the next axis and repeats this scenario. This is the reason that the N/C limit switches can be connected in series an all connect to one input.

[ShawnM]

I had the same question when I started wiring these home switches. As Shawn mentioned "The Acorn homes one axis at a time. With all switches in series the loop is closed". What I did not realize is that immediately after Acorn homes a switch and opens the normally closed limit switch, Acorn moves the axis a millimeter or so in the opposite direction which closes that limit switch. Once the limit switch is closed, Acorn moves on to the next axis and repeats this scenario. This is the reason that the N/C limit switches can be connected in series an all connect to one input.

That is correct, I guess I should have explained it a little better, thanks. Always use NC switches for limit and home switches. Why you ask? Section 5.7 of the Acorn manual even states:

All inputs used for Limit and Home switches should be of the normally closed type switch. The switch should be closed when the machine is in its operational state. Note: Using Normally Open switches for Limit or Home switches is dangerous as the machine will not stop in the event of a wire break or switch failure. Using NO switches also introduces more sustainability of electrical noise causing an erroneous input trigger.

[suntravel]

Thanks, had made the same thoughts later, one axis opens the loop, moves back than closes it again.

Must submit the machines in my job are moving all axes the same time for homing, so each needs an extra input.

Kind regards

Uwe