How to wire two limits in series?

[bgolash]

Hi
I`m a newbie in electronics so please bear with me.
I`ve heard that its sometimes necessary to wire limit
switches in series to share one input on the breakout
board. I`m using the sound logic board.
Is this correct: Do you take the wire in my case I`m
using a 3 wire cable and run it into a junction box then
wire the 3 wires from the photointerrupter to the junction
box and just wire them...matching the colors together.
I`ll have two photointerrupter that need to be wired per axis.
Specs on the photointerrupter
http://rocky.digikey.com/WebLib/Shar...ta/gp1s73p.pdf
Thanks for the help.

[CJL5585]

What you have heard about wiring limit switches in Series is TRUE. However, it applies to limit SWITCHES and not to photo interrupters.

Most limit switch circuits are wired in series with the limit contacts being normally closed. A limit condition opens a switch which causes a machine disabling condition.

Electronic devices do not operate well (IF AT ALL) in series operation.

A limit switch is used for safety purposes. SAFETY circuits by law are required to be designed to be FAILSAFE. That means that if anything happens to the voltage, components, wires, etc. that the circuit will cause a shut down in a mode that is safe. (like the limit switch circuit)

There are "shade tree" methods to rig a circuit, but may or may not be dependable and repeatable. I would not recommend them as a safety circuit, and for that reason, refrain from doing so.

Hope this helps.
Jerry

[Al_The_Man]

The components shown in your case make it a bit tricky to connect in series as, for one, they are 'operate on light' devices so that means the output transistor will be on until tripped, the fact that the led cathodes and the transistor emitters are common, make it difficult to set up an AND condition without extra components, which would have to be done if you wanted one input to register when either one switched off.
Al.