Hi wireless techs, I have a weather station which sends RS232 data. I need to get the data to another RS232 device which is about 60 metres away and there’s zero possibility of hard wiring it. I’m looking for a simple way to RF the data across. It only needs to be one way; no data or commands come back to the weather station. Flow control is not required either. I’ve seen some devices which work in the ISM 900MHz or 433MHz bands but they are overkill for this simple setup (not to mention hundreds of dollars) I’ve considered [[u]these types of devices[/u], but I’m not sure that they will be reliable enough over 60 metres (with trees in the way as well…)
Most of the very low cost RF transmitter/receivers use OOK modulation and do not work well with just asynchronous data. The data needs to be encoded (Manchester works) plus have a preamble sequence sent for the receiver to ‘lock in’. Search for these terms and you will find much discussion and solutions in the SparkFun forum and other places on the web.
The simplest is to use two XBee series 1 modules set-up in ‘transparent’ mode. These do have two way communication you don’t need but this allows the modules to ACK reception of data and retransmit in the event of errors or interference. Again lots of discussion about using XBee in this forum.
robbage:
Hi wireless techs, I have a weather station which sends RS232 data. I need to get the data to another RS232 device which is about 60 metres away and there’s zero possibility of hard wiring it. I’m looking for a simple way to RF the data across. It only needs to be one way; no data or commands come back to the weather station. Flow control is not required either. I’ve seen some devices which work in the ISM 900MHz or 433MHz bands but they are overkill for this simple setup (not to mention hundreds of dollars) I’ve considered [[u]these types of devices[/u], but I’m not sure that they will be reliable enough over 60 metres (with trees in the way as well…)
Thanks Steve and Waltr. My experience with xbee is zero so I wasn’t sure if that was even an option. Time to start doing some reading. Retransmit on error would be handy as well.
robbage:
Thanks Steve and Waltr. My experience with xbee is zero so I wasn’t sure if that was even an option. Time to start doing some reading. Retransmit on error would be handy as well.
Many thanks.
The XBee uses IEEE 802.15.4 (as do others' products) and that '15.4 protocol has an option, usually enabled, to do error detection and correction via retransmissions. Packetizing, error correction, listen-before-transmitting, and on and on is why these module make plug-and-play. Versus weeks or months if you start with a bare radio chip.
![[u]these types of devices[/u]](http://2.imimg.com/data2/VD/BY/MY-1516436/rmd-4fz-rx_250x250-250x250.jpg){kind=link}