CNC over wireless

Has running a CNC machine wirelessly every been successfully achieved with a similar error rate that wired machines experience? In other words, wireless with no error in an industrial environment. And I am referring to the connection between the actual CNC equipment and the PCs that drive them.

I have seen this attempted with dismal results. And following the failure, a football field's length of Ethernet cable was strung to the ceiling. But with Zigbee, Wireless-N, and others, there has to be a decent solution by now?

Cabe

0 Chris_Pinter over 16 years ago

Hello Cabe,

      This is Chris Pinter. I am the senior RF engineer with Pinter Electronics Consultants.

      I do not think we will ever see reliably communication via wireless. The reason is because there is so much noise in the environment. The wireless channel is incredible hostile. There is noise from motors, lights, AC lines running through the wall as well as Wi-Fi, zigbee, cellular telephones, etc. These same noises affect wired communication as well. However, we are able to control the wire much better.

      There are some great techniques used to limit this noise including twisting the wire, wrapping a shield around it, and a ferrite core etc. In a sense, we are creating an environment to transmit the information by putting a barrier between the noise source and the signal we want to transmit. We can do this as well with radio waves but it requires the use a waveguide which effectively shields the signal from the noise as it travels from the source to the load.    Unfortunately we cannot apply these same measures to the free space of an office building or machine shop.

      I would say that a machine shop would have much more noise than an office environment because of the motors used in the CNC machine.    So you would be best to use wires instead of looking for a wireless solution. At least the Ethernet cable limits the amount of noise affecting the signal.

Hope this helps,

Chris Pinter

When your radio absolutely must work. You need a specialist.....Choose the best.

http://www.pinterec.ca
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 Former Member over 15 years ago

Hi Cabe

Here is a U tube video of our Bluetooth Adapters being used for cable replacement for CNC machines. This is a common application for our Bluetooth Adapters, even in the noisy CNC environment. http://www.youtube.com/LMTechnologies62

Most companies select the LM058 Bluetooth Adapter as it has an external antenna which you can change to match the range you require. http://uk.farnell.com/jsp/search/results.jsp?N=0&Ntk=gensearch_001&Ntt=LM058&Ntx=mode+matchallpartial&suggestions=false&ref=globalsearch&_requestid=779818&isGoback=false&displaytext=&isRedirect=false

Kind regards
Hazel Doughty
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 Catwell over 15 years ago in reply to Former Member

Hazel,

Thank you for the reply and solutions. Bluetooth in CNC applications, I never even thought to look into it.

I've read that the up and coming Bluetooth revision increases distance too.

I will have to look into this.

Cabe
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 Former Member over 15 years ago in reply to Catwell

Cabe

The way to increase the LMT Bluetooth Adapter LM058 range is to change the antenna. The Bluetooth module inside the adapter is Class 1 which with the standard 2 dbi antenna is up to 100m range. You can select from a range of antenna includnig a 9dbi antenna http://uk.farnell.com/lm-technologies/lm254/antenna-whip-sma-connx-9dbi/dp/1790359?Ntt=LM254 and if the adapter is surrounded by metal or any other environment where you would want the antenna to be away from the adapter you can use the magnetic base http://uk.farnell.com/lm-technologies/lm242/base-unit-sma-connx-w-1-5m-cable/dp/1790360?Ntt=LM242

So dependant on the environment and the application you can select the adapter and the antenna to match your requirements.

Hazel
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 Chris_Pinter over 15 years ago in reply to Former Member

I would agree.

Bluetooth uses Frequency Hopping Spread Spectrum.(FHSS) modulation. This is a vry effective method of transmitting information in noise environments. The reason is because it has a very narrow bandwidth.

The biggest problem, as I mentioned before, is the environmental noise. The CNC machine will generate noise as it uses a motor to operate. A class 1 bluetooth device has an output power of 100mW. FCC will restrict a commercial device to use a specific antenna. You cannot just change an antenna on a device in order to get better gain.....This is only true on products that are already being sold.

If you have the intention to design and build your own bluetooth device then you will need to investigate the radiated emissions using the antenna you want. Again FCC may or may not allow this device to be sold.

Hope this helps,

Chris Pinter
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel