Is there any Wireless Safety Systems out by Banner, AB, etc.

[Baker in Virginia]

Good Morning ,

Do you folks know if Banner , AB , etc. as come out with any Wireless Safety Systems , or do you think that with never happen ? I know there has been some big advancements in wireless systems in industry , but not sure if it as gone far enough for safety systems.

Thanks,

 

[mk42]

Short answer: Siemens does. Both wireless HMI's with estops and enable buttons, as well as for normal safety IO traffic.

A couple marketing pages:

http://w3.siemens.com/mcms/automati...es/functional-safety-safety-via-wireless.aspx

http://www.industry.siemens.com/top...-safety/safe-communication/pages/default.aspx

Long answer:
Profisafe is actually network independent/agnostic. It doesn't care what physical medium is used, as long as the data gets there. If enough packets are missed in a row, then a watchdog timer is tripped, and the PLC and F-IO recognize this, and take the determined safe action automatically.

It WILL go to the safe state when it thinks it needs to. The trick with wireless is getting a stable enough connection for that to rarely/never be necessary. This can be challenging with normal DCF and 802.11, what everyone thinks of when they think of wifi. The trick for controls is that it is a shared medium, and any device can try to broadcast whenever they want, interfering with the others. Siemens sells wireless devices that can use a different part of the 802.11 standard, PCF (technically it is a proprietary extension called iPCF). It turns wireless into something like a token passing network, where the master (access point) tells each client when it's turn to talk is, for only 2ms. After each client communicates, it starts over at the beginning of the list again.

2ms isn't long, but it's plenty of time for one PLC scan's worth of IO traffic.

It also supports rapid roaming, so IO can move from access point to access point without triggering a watchdog. I've seen this used in many monorail and AGV applications, where the local safety IO was constantly on the move over a large area.

 

[Timbert]

As Mk42 says, it's already happened. Both ProfiSafe and CIP safety (used by AB) can be used for up to SIL3 rated functions.

I think the bigger hurdle is getting engineers used to the idea and that safety signals across wireless networks can be as safe if not more safe than traditional hardwired installations.