connecting switches to a DeviceNet allen bradley ArmorBlock Maxum 16 input module

I have a Cat # 1792D-16BVTOD ArmorBlock Maxum 16 input module for Device net.

There are already several magnetic reed switches connected to this thing, and I want to connect a relay contact out of pin 1 on the module's ports and back to pin 2.

After looking throught the manual, I finally called tech connect. the guy told me I can just connect a switch between the two. I talked to three people about it and none of them seemed too sure to me.

It gives maximum current levels for the module, and it talks of short circuit sensing....

is there something in the module that limits the current?

how does it know the difference between my switch and a short citcuit?

Thanks.

If you connect a relay contact or mechanical switch across pin 1 and 2 (or pin 1 and 4), you are not creating a short circuit. You are simply directing the source voltage to the input logic in the module which probably consists of optoisolators and certainly has the necessary current limiting resistors.

The "maximum current levels" that you mention probably specify how much of the source voltage's current can be consumed by sensing devices. In your case it's negligible since you just have a dry contact.

A direct short would be created if you connected pin 1 (source voltage) to pin 3 (return), or if either of the inputs (pin 2/4) was energized and made contact with pin 3.

thank you