On 7/2/2014 1:29 PM, Jean-Louis Oneto wrote:
Hello,
AFAIK, the differential variant of RS-232 is RS-485. I'm not sure about the 
levels.
Best regards,


Jean-Louis Oneto
You have to control the direction of RS485. You don't have to with RS232. One of the problems with support of RS485 in Linux OS kernels is that the kernel can't respond to the turning of the line quickly enough in real time. I had an application with 115k requirement, and it had to turn the line within 1/10 of a bit time. Pretty quick for a kernel.

It is differential, and it does send data, but is a different beast in many ways.

I would have liked to have had an external processor to handle the RS485, and some chips do that, but we had the engineer just attach two serial ports on an Arm SOC to the usual serial uarts, and it was fun figuring out how to make it work.

BTW this was for communicating with an airframe, and the avionics dictated the rate we had to turn the lines. It was for passenger signals, etc., so was simple, but you basically ran all the cabin lighting and attendant signalling thru one line for the entire aircraft.
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