Electronics > Projects, Designs, and Technical Stuff
RS485 signalling characteristics - collisions
<< < (3/5) > >>
Simon:
Yes but if the output drivers are H bridges as shown on some data sheets then clearly even an outputted "1" is being hard driven even if as idle the bus may sort of float there.
ogden:

--- Quote from: Simon on May 09, 2020, 12:45:08 pm ---Yes but if the output drivers are H bridges as shown on some data sheets then clearly even an outputted "1" is being hard driven even if as idle the bus may sort of float there.

--- End quote ---
Every node including master have option to go into RX mode with TX driver in high impedance mode. So in theory bus can "float" indeed. Thou usually master is always in TX mode and goes RX only when slave is expected to TX. Could you give some hint - what rs485 will be used for?
Simon:
Oh I have no use for it here and now. I am just working my way through the UART capabilities on the SAMC. RS485 will be used on devices I work with at work so understanding it is good. I am also looking at Lin to better understand how to use the SAMC UART in lin mode as I will be working on that in the future.
MosherIV:
Hi Simon.
I think RS485 is meant to be point to point not a bus, so it is not possible to have bus collision.
If the system has multiple nodes, then each node must have an input and an output RS485.
Each node must know if it is the node being communicated to or it must forward the data stream.
RS422 is the bus version of RS485, no idea how it deals with bus collision, when I used it, we just used it as a RS485 protocol analyser, so the analyser did not cause bus collisions.
Simon:
RS422 just splits transmission and reception to the master, it is still master slave. It just means that as the master sends data the slave can send data back. Given that RS485 should not be expected to operate in collision mode it should also be a master slave system like lin.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod