Serial port Access on Wi-9P

Digi Remote Manager Device Manager
1

Hi all.

I’m trying to write a device driver (via python) for the iDigi platform on my Wi-9P.

How can I access Port 1 of the board from my driver? Mainly, what is the device name of the serial port?

Thank you.

2

Hi,

It looks like the serial ports should be named /com/0, /com/1, etc.

For more info you can take a look at the following page: http://www.digi.com/wiki/developer/index.php/Connect_Port_Serial_Port_Access

Chris

3

Thanks cpopp.

One weird thing I see now is that I’m dropping a lot of data. I’m running fairly low speed (9600bps), and my data tends to be short bursts of only about 20 characters every few seconds.

What sort of buffer/fifo is in effect?

4

One idea (hardware related) - are you using RS-232 or RS-485?

An RS-485 line without proper grounding can appear to ‘drop’ blocks of data.

An RS-232 line with improper cabling (long length but TX to TX instead of TX to RX) can appear to move say 95% of the bytes due to capacitive coupling, but will drop bytes.

Not saying that’s the issue, just something to check based on my 30 years of doing serial communication trouble-shooting.

5

Hi lynnl.

Thanks for the ideas. I’m running RS-232.

After stuggling for a while trying to find the problem, I discovered the other device relies on the host supplying its transceiver with power via the RTS line (it’s a old consumer device). It’s odd it even worked at all (though it’s possible it was only necessary to keep the charge pump caps full for “longer” bursts of data). As soon as I asserted the line though, everything went to normal and I’m getting clean data now.