Hello,

I have a BeagleBone Black with a "Serial Cape" 
(http://www.logicsupply.com/eu-en/cbb-serial/). This cape supports RS-485 
which i'm interested in. Before i had this cape, i used a 
RS-485-to-USB-converter.


My problem:
I try to read some data from an external device. It's very simple: The 
request is just "/?!\r\n" and then i get the data.

With the RS485-to-USB-Stick i used this serial port configuration (with 
ser2net):
/dev/ttyUSB0 9600 7DATABITS EVEN 1STOPBIT

With the cape i tried this configuration:
/dev/ttyO4 9600 7DATABITS EVEN 1STOPBIT

Unfortunately this first try didn't work. I didn't get any response. I also 
tried this configuration:
/dev/ttyO4 9600 7DATABITS EVEN 1STOPBIT RTSCTS

I set the jumpers on the cape like this:
J8: RS485
J7: UART4 RTS

The RS485+ wire is connected to the RS485B port, and the RS485- wire is 
connected to the RS485A port.
(https://docs.google.com/document/d/1sgurQ-7gLyn7g-Kg983NRM0aDkYEqHqy9dmrieX_RUM/edit
 
page7)

To get a better overview i made a photo:

<https://lh3.googleusercontent.com/-DGOBBHIo6sM/Vd1xuVsgc_I/AAAAAAAAAEE/JS4oAhPYoOk/s1600/IMG_20150826_091607_mod.jpg>


At the bottom of the picture there is the RS485-to-USB converter. It just 
has two ports which i used to connect the RS485 wires.

I think the board itself should work, because if i execute "cat 
/sys/devices/bone_capemgr.*/slots" i can see it.

My question:
Do i do something wrong? Maybe someone else has used this cape with RS485? 
I thought it should be almost as easy as with the USB converter?


Thank you for any help

Best regards
Benj

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