Serial port IO question

[pehr anderson]

Dear David,
Don't forget, you have to set all the serial port parameters correctly.
The easiest way to do this is with stty. For example, under linux add the
line:
    os.system("stty 19200 raw < " + upsdev)
You need to find the appropriate speed of course...
For more information see "man stty"... it's not very informative but at
least it works.
    -pehr


David Stokes wrote:

> I am attempting to send a ^M (Control-M) down a serial port and then
> read back from that same port.  The application is an old UPS that will
> send back system status after a ^M.  The code below opens the port but
> the readline seems to be returning what I wrote.  My guess is that I
> haven't really grabbed I/O stream for the read operation.  Any
> suggestions?
>
> Dave Stokes
> -------
>
> #!/usr/bin/env python
> import sys, string
>
> upsdev = "/dev/ttyS1"   # Serial port attached to ups
>
> class   get_ups:
>     def __init__(self):
>         print "Getting ups status"
>
>     def get_ups_data_p(self):
>         upsdata = open( upsdev, 'r+');      # open port to ups
>         upsdata.write("\015")                   # send ^M to ask for
> status
>         upsdata.flush()
>         upsbuffer = upsdata.readline()       # get status back
>         upsdata.close()
>
> if __name__ == '__main__':
>     ups_status = get_ups()
>     ups_status.get_ups_data_p()