Your argument makes sense. Perhaps wireless is not yet as reliable in some environments as needed in order to replace wiring. But I have replaced a lot of wiring with wireless in manufacturing plants and tank farms. I have integrated Allen Bradley PLC units into a networked architecture where the PLC is on the network and can send and receive data that can be operated on in approved locations. Real time operations, like pumping, mixing, pressure regulating and so on are carried out by the local PLC. Production rates, failures and other product information is sent over the network and also to a PLC that controls production floor score boards that everyone can see, and also to the office of various managers and exec's. The network is an intranet rather than an internet. PLC's are pretty reliable in most noisy environments but they are not as powerful as computers. For places like Class 1, Division 1, Group C explosive environments, intrinsic safety is still the general rule but in some cases optical logic and fiber optic is used, and also wireless. However, regulations still require normal hard wired fail safe. But perhaps wireless is not widespread as I may have imagined based on limited number of installations. ----- Original Message ----- From: "Vasile Surducan" To: "Microcontroller discussion list - Public." Sent: Sunday, November 30, 2008 4:33 AM Subject: Re: [PIC] Comparing a PIC with a PLC > My opinion is that wireless will never replace entirely the wired > industrial applications. > Even the OFDM seems to be the right solution for noisy environements, > don't forget in industry is room for any kind of personell not only > (smart) engineers. A wireless transducer communication problem is much > difficult to be solved. The technician must have expensive tools for > solving minor communication problems which behaviour have nonsense for > a person without a small experience in RF (propagation, atenuation > measurements, modulations etc). > > Imagine just a place where a welding machine is running continuously. > Tesla lovers knows what that means as RF spectrum. Any Zigbee will be > unuseable there. Even OFDM will probably cough. > > Vasile > > On 11/30/08, Rich wrote: >> Perhaps. >> ----- Original Message ----- >> From: "Xiaofan Chen" >> To: "Microcontroller discussion list - Public." >> Sent: Saturday, November 29, 2008 9:00 PM >> Subject: Re: [PIC] Comparing a PIC with a PLC >> >> >> > On Sun, Nov 30, 2008 at 7:57 AM, Rich >> > wrote: >> >>. Some mention on >> >> this list about 4-20 mA piqued my interest because wired systems are >> >> being >> >> phased out and replaced by reliable wireless systems. Some systems >> >> are >> >> already using satellite data communications. I can see a time when >> >> HART >> >> protocol will become obsolete. >> >> >> > >> > That is your wish. HART will be there for a long long time. Wireless >> > will >> > take years (or 10 years or 20 years) to replace wired systems. Even >> > then >> > Wireless HART is the leading candidate in wireless world in process >> > automation. >> > >> > Xiaofan >> > -- >> > http://www.piclist.com PIC/SX FAQ & list archive >> > View/change your membership options at >> > http://mailman.mit.edu/mailman/listinfo/piclist >> >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist