Hello DoF Community,

I am working on a project where I am using a UR10 Universal Robot. I want the station to operate as normal and have a SICK S300 Laser Floor Scanner wired into to Robot Controller dedicated safety I/O. When the floor scanner area is entered. I want the Robot to go into safeguard stop and be prevented from moving until the area is clear and the safeguard stop is reset.

The issue I am seeing is that I am seeing the robot hesitate and enter safeguard stop when nothing is in the floor scanner area. It seems that I am seeing a blip on the voltage every 125ms which I can see on oscilloscope which causes the robot to enter safeguard stop and then need resetting.

Should I be able to wire a scanner like this directly into the Safety Controller, or do I need to do anything with the signal coming from the floor scanner. Does anyone have any experience of using this type of floor scanner wired directly into the robot safety controller. I am reluctant to wire it differently as to me the safest way is floor scanner signal directly into the safety on the robot controller.

Thanks for any help

Jack

We've encountered this issue a number of times, with various pieces of safety equipment. we initially blamed it on the pulse testing used on many safety outputs, like the blips you're seeing here. However, even with pulse testing turned off, we've seen 'phantom' safeguard and emergency stops occur. UR support have advised us this is a result of using OSSD or semiconductive outputs. We've addressed this issue by using a safety relay to filter the signals going to the robot. This also has the advantage of allowing you to reset the relay rather than the UR, and save some I/O. It is also possible to purchase Low Pass Filter terminal blocks from Pilz, which have worked for us in the past.

Thanks for your response. Would you be able to attach any wiring diagrams and let me know which safety relay you have used. We have tried numerous things today with a Pilz PZE X4P but still getting a fault.

I can't share any wiring diagrams unfortunately due to confidentiality considerations. We use the Pilz PNOZ S4, which can accept dual channel inputs from the safety device, and has 3 N/O contacts which can be used to switch the robot inputs. From what I can gather online, the PZE X4P is a relay expander, so it won't work without another safety relay. A pair of normal relays will work for a proof of concept too, but wouldn't be acceptable on a factory floor (assuming you're adhering to safety standards).

@Fionn_Merz

How is your robot working with the safety relay?

It seems to working fine now. We did as suggested and filtered the signal through a coil of a safety relay. It now seems to work as expected.

We use either a UE`10-2OS or UE48 relay depending on if you need field set switching for a maintenance mode safety field. The wiring of these is pretty start forward just make sure that you tie your DC reference voltages together so the robot will see the change in potential state when the OSSDs switch.