Radio Modems

[Dave Flowerday]

As an alternative, you could use the tether port instead. It has RS-232 on it and I'm nearly certain that the command handshaking which is sent to the radio modem is not sent when using the tether. Also the OI and RC switch to tether mode when they see a certain tether pin pulled high. We did a project a few years ago where we built ourselves a field control system, and to do it we used old PBASIC RCs at each end of the field and a control computer which talks to them over the tether port using RS-232 (pretending to be an OI).

It's been a few years since I looked at this but you should be able to figure out which pin fairly easily.

It's worth pointing out for anyone following along in this conversation that attempting these types of things will probably void your IFI warranty. If you hook things up to the wrong pins there's a good chance you can do damage.

Originally Posted by DeepWater

Other than this the only interesting tid bit of info I have found out is that there is no CRC check performed on the 26 byte data packets.

As a side note, the RC does checksum the data after it is received (there are two checksum bytes in each packet), so corrupted data shouldn't be a concern. I assume the checksumming is not done in the modem for latency reasons. If the modems you're looking to use have a config option for it, I'd turn off any checksumming and retransmission that they may do to achieve the best latency.