I am trying to implement a system that works with RS485 and make it work in a wireless fashion.
I have a coordinating node that polls three handsets and asks for information back. The packets are very small (just a few bytes), but I need to have a very fast turnaround of data. It needs to be around the 1-2ms region. With the RS485 version, I can see the data coming back to the coordinator in a few microseconds, but with the first module we have tried, despite being told by the distributor it would work, it takes something in the region of 20ms just to process a tiny packet of information. The coordinator needs to get way more interrogations of each node per second than a 20ms turnaround gives.
Would any of these Digi modules be at all suitable? Basically I am just looking for wireless UARTs where it takes a very short time to process the radio information and pass i though to my micro.
I can’t see how any wireless solution would meet your needs as stated. All wireless systems are subject to interference, which means it can take an arbitrary amount of time for a message to get through.
The 20mS turnround sounds about right under normal circumstances. If you want more information on that, check out the product manual.
As far as I understand it, there should be ways of hugely reducing a 20ms turnaround. I know from previous training sessions I’ve had with RF chipsets from my last job that you can certainly get data in and out massively quicker than that. The problem is when you build in stacks, address and very strict error checking.
I don’t want all of that, I certainly don’t want big, complex stacks and I don’t want complex error checking. For my app, I want each transceiver just to be able to send a few bytes out and each transceiver receive all bytes and pass it on to the micro it’s connected to. My volumes aren’t big enough to go to chipset level.
