Strange behaviour of CLING together with termios (RS232-connection)

Cling
1

Hi ROOTers,
I’m trying to connect a HP 33120A wave-generator via RS232 to my computer.
I wrote a very simple c program, which works pretty file (see hp33120.c)

when I’m trying to put the content of the program into a C++ class and provide this to root the rs232-io behaves very strange:
The device has problems to interpret the code, so I put a logic analyser to the TX-line and put the output in the attachement. As you can see I tried to write “SYSTEM:REMOTE\n”. In case of the simple c program it works fine, running over CLING with the test-script it generates strange bit-patterns at the beginning (here are two bit which should not be), because of this everything is shifted and the code cannot be interpreted correctly anymore. I tried to make workarounds with usleeps, but its not working.

Please tell me if you have any hint

Georg

RS232-not-working.png1292×82 8.15 KB


testRS232.C (281 Bytes)
RS232Link.h (1.61 KB)
RS232Link.cpp (3.14 KB)
hp33120a.c (4.58 KB)
RS232-working.png1208×83 7.48 KB

2

Hi,

No idea. Maybe try valgrind? I’d suspect a memory issue.

What happens if you rename your main() into hp33120a and then just run
.x hp33120a.c

  • does that work?

Cheers, Axel.

3

It seems that the delta in the signals (visual inspection) is also increasing with time (?)

If I were you, I would look at what causes the initial discrepancy and take it from there.

_sk

4

Hi Axel,

thanks for this hint to run the c-prog in CLANG… yes this works…

I checked some much older projects I worked on before and found another RS232-class. I copied some lines together and it seems to work - sorry the code is ugly, but it works! I didn’t check the receive function so far, seems I implemented some special cases here in order to allow a line-end which is not the message-end.

I do not understand the difference so far… at the moment I am happy its working.

Georg
RS232Link.cpp (4.87 KB)
RS232Link.h (2.12 KB)