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Wireless Transmitter/Receiver

Wireless Transmitter/Receiver

Wireless Transmitter/Receiver

Hi All - The project has a signal that would be stationary but the DAQ will move. Distance will be less than or equal to 1000 meters, and could be much less but nominally 500 m. I don't like wireless and prefer to use actual signal wire however that might not be an option. Can anyone recommend a cheap robust NEMA 4X wireless transmitter and receiver for a 4-20 mA signal appropriate for an industrial/agricultural site? Looking at Omega Engineering something like the zED-P Series or ZW-ED Series except I don't like the web server - I just want simple, easy to use, easy to support and troubleshoot. Is the 2.4 GHz IEEE 802.15.4 transmitter the best option for the price and distance or can someone recommend a different protocol/technology? Is 900 MHz better for longer distances like this? Outside the US, is 900 MHz a problem where 2.4 GHz is unregulated? Would you say the Wireless HART transmitter from Phoenix Contacts pn RAD-WHA-1/2NPT - 2900100 is the 'industry standard' and a good default option? Or any other thoughts/comments?
Thanks in advance.

RE: Wireless Transmitter/Receiver

There are a whole lot of these systems used for controlling wells. A tank on a mountain farrrr away needs to tell the well pump to start/stop. These systems are quit robust and I've never seen a problem with them.

Here's one example: Note the graphic shows the typical ON/OFF kind of control but the text speaks mainly of 4-20mA.


Keith Cress
kcress - http://www.flaminsystems.com

RE: Wireless Transmitter/Receiver

>Is the 2.4 GHz IEEE 802.15.4 transmitter the best option for the price and distance or can someone recommend a different protocol/technology?

Answer: When you are in the US, use 900MHz because it is FAR AND AWAY the best band for the data that's being generated - small amounts of data that needs punch through ability in all weather. Signal strength counts and 900MHz beats 2.4GHz. 2.4GHz is great for file downloads and web pages, but process data is a couple integers or a floating point value so the bandwidth of 2.4GHz is just not needed. 2.4Ghz sacrifices signal strength for bandwidth.

>Is 900 MHz better for longer distances like this?

Answer: Absolutely yes.

>Outside the US, is 900 MHz a problem where 2.4 GHz is unregulated?

Answer: Very likely, 2.4GHz is widely used outside the US with the attendent loss in distance and signal strength. Depends on the county.

>Would you say the Wireless HART transmitter from Phoenix Contacts pn RAD-WHA-1/2NPT - 2900100 is the 'industry standard' and a good default option?

Answer: absolutely NOT for a couple reasons
- 2.4GHz
- need a HART gateway/wireless access point
- probably need a HART configurator to make the adapter run
- you can't get what want from HART - a HART gateway output is Modbus/OPC, not an analog 4-20mA, which is what you want
all of which are absolutely unnecessary unless you like expensive toys.

What you want is wired-in/wired-out. Three choices I've used below. All work.

Phoenix Contact used to have a pair of 1 Watt 900MHz one-way radios, so-called electricians radio, because even an electrician could figure it out.: the field transmitter is a NEMA 4 'beer can' with an omni antenna with a conduit threaded fitting and flying leads, the receiver is a DIN rail mount receiver on the other end. Wired-in/wired/out. 4-20mA in/4-20mA out. Obviously the radios need DC power as well as the field transmitter.

Banner has a pair of 1W 900MHz radios that are NEMA 4 but their plastic cases really need to go into a panel when outdoors. Bidirectional 4-20mA and a pair of DI-DO: an PNP transistor at the receiving end follows the state of dry contact DI at the transmitting end. The Pre-Mapped pair of radios does not require software, just some button pushing to tell which network layout to use. Excellent performers.

Precision Digital has a pair of 900MHz radios, integral omni antenna, in very nice EX housings (no FM approval) that are clearly weather proof. But the radio power is only 1/4W not 1W. I just used a pair as RS-485 modems for a 300 foot shot and they worked out-of-the-box at 19.2K baud. The radios have a bidirectional 4-20mA wired-in/wired-out and an absolutely useless DO at 3Vdc (like what do you do with that?). When both ends need to be outdoors those screw cover EX housings are tough as nails. Model PDW30 or something similar. For a mobile app, I'd probably stick with a 1W radio.

RE: Wireless Transmitter/Receiver

Thank you for the post danw2, very good info. This will be used in Mexico, any experience with 900 MHz regulations there? I read something about 1 yr to 18 months for approval time.

RE: Wireless Transmitter/Receiver

Mexico? I have no clue since I have experience in the US only and no experience with 2.4GHz.

Banner does have wired-in/wired/out radios in the 2.4GHz band. But the power output is quite different, a full 1 watt at 900MHz and 65mW at 2.4 GHz.

Is the opportunity big enough to justify testing a pair of Banner Pre-mapped 2.4GHz radios? They cost about $850.

RE: Wireless Transmitter/Receiver

It's not my call, so just gathering options. Thanks again.

RE: Wireless Transmitter/Receiver

From your first option above, this looks promising and can be used in Mexico but it's a little expensive, has extra DI/DO and only IP 20 : Phoenix Contacts RAD-ISM-900-SET-DC-UD - 2867034

RE: Wireless Transmitter/Receiver

>this looks promising and can be used in Mexico: Phoenix Contacts RAD-ISM-900-SET-DC-UD - 2867034

That's the beer can radio I described above. That unit has worked on in mobile service - a construction site. But it's 900MHz and the question is whether that's legally useable as unlicensed radio in Mexico.

RE: Wireless Transmitter/Receiver

Yes, that's the problem - the NOM listing in Mexico. Here is the Precision Digital you were talking about as well:

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