Hi,
I am currently running devc-ser8250 with one of the com ports being rs485.
After scoping the lines, we found out that the line (differential between
data + and data -) shows data flowing when we send data on the com port.
When I am not sending any data, rs485 port keeps the line high which is
wrong for rs485. The sender (master) should be letting go of the bus after
sending. Is this a software issue where there is something I need to do with
stty or devctl to make the serial port let go of the line? Or is this a
hardware issue?
Some info:
The computer is a nova8890 with a com port that has 4 data wires (tx+, tx-,
rx+, rx-) and we are using it to talk to a device with 2 wires (+,-).
Khian Hao
For RS-485 you need to control this yourself (usualy via DTS/RTS I think )
Hardware doesn’t know when to drive the line or not
“Khian Hao Lim” <khianhao@stanford.edu> wrote in message
news:bqmqnn$d5u$1@inn.qnx.com…
Hi,
I am currently running devc-ser8250 with one of the com ports being rs485.
After scoping the lines, we found out that the line (differential between
data + and data -) shows data flowing when we send data on the com port.
When I am not sending any data, rs485 port keeps the line high which is
wrong for rs485. The sender (master) should be letting go of the bus after
sending. Is this a software issue where there is something I need to do
with
stty or devctl to make the serial port let go of the line? Or is this a
hardware issue?
Some info:
The computer is a nova8890 with a com port that has 4 data wires (tx+,
tx-,
rx+, rx-) and we are using it to talk to a device with 2 wires (+,-).
Khian Hao