You need a service tool to access the I/O's. Unfortunately the SL was short lived. They run well, but when there is a problem you need to have a tool. I don't think there is an after market tool on the market because there were not that many made. You should have an interface board mounted on top of the 104 door board. this has LED indicator's on it. D24 is the Door Edge indicator, if it is on the Beam is broken.DO10 is the door open output indicator D7, if it is on the door is trying to re-open. You really need a Manual and a service tool for this bad boy. You may have a parameter or timer out of whack, which again you need a tool. So let me reiterate. You need a tool. Good Luck.