I had a unit in the field that was having communication issues (timeouts) when the speed was set to 9600. This is a very simple rs485 network with just two devices. The master is set for very long timeouts (on the order of 5 seconds). I don't have any information regarding the timeout parameters of the slave, but I'm not sure it's applicable.
When the baud rate was set to 9600, I was getting timeouts on the master pretty frequently. In the past, this master has been working just fine with other devices at 9600 (not the same manufacturer). On a whim, I changed the baud rate to 19200 and magically, there were not any more timeouts anywhere. I moved it back to 9600, and the timeouts returned.
The messaging is not complicated whatsoever. And the spacing between messages from the master is very relaxed (as in the next message would go out 500mS after a good response is received.)
There also aren't any gaps in the outgoing message whatsoever. I don't have access to the unit in the field, but one here shows a nice clean outgoing waveform at both baud rates.
The cabling is good and termination present on both sides (run is only a few dozen feet, so no biggie anyway). The pullup/pulldown is also taking place on one side.
I'm at a loss to explain why increasing the baud rate would help this system? Anybody have any ideas?
When the baud rate was set to 9600, I was getting timeouts on the master pretty frequently. In the past, this master has been working just fine with other devices at 9600 (not the same manufacturer). On a whim, I changed the baud rate to 19200 and magically, there were not any more timeouts anywhere. I moved it back to 9600, and the timeouts returned.
The messaging is not complicated whatsoever. And the spacing between messages from the master is very relaxed (as in the next message would go out 500mS after a good response is received.)
There also aren't any gaps in the outgoing message whatsoever. I don't have access to the unit in the field, but one here shows a nice clean outgoing waveform at both baud rates.
The cabling is good and termination present on both sides (run is only a few dozen feet, so no biggie anyway). The pullup/pulldown is also taking place on one side.
I'm at a loss to explain why increasing the baud rate would help this system? Anybody have any ideas?