Motion Failure Alarm - Relay Control

Hi, (sorry if this has been covered - i did search)

I'm trying to build a motion failure alarm.
There are quite a few on the market, but mostly for rotational motion, and large applications. This is a small application and the movment is linear - back and forth. My initial thoughts are to use a photoelectric motion sensor, and a control unit which will sound an alarm if motion isn't detected after 5 seconds or so.

I've got various options. But i'm currently considering an SSR timer relay - which does all the processing for me. It switches if no pulse is detected for a certain time.

Here's my current question. The input for the relay is based on a switch - it detects a pulse if the 2 input contacts are connected. Most of the motion sensors that I can find send a voltage to an output. I'd rather not use another relay. There are some with 'open collector' outputs, which (if i'm correct) connect the collector to ground when tripped.

Can I connect one of the relay terminals to ground and the other to the collector output of this sensor?

Maybe. Can you post links to the SSR timer relay and the motion sensor you're looking at?

Ken