Socket Communication with Matlab

Technical Questions Robot Communication
1

Hi there,
I try to implement to read data streams from the UR controller using the socket interface and port 30003. To do this I’m using Matlab. If I want to read the actual position in X for example I read Byte 444-451, like described in the Client_Interface_V3.5.xls and convert it to a floating point number. But the value makes no sense. Here is my example code:

socketClientRTC= tcpip(TCPclient, 30003, ‘NetworkRole’, ‘client’);
fopen(socketClientRTC);
data= socketClientRTC.fread;
dataCartPosX= [uint8(data(444)) uint8(data(445)) …
uint8(data(446)) uint8(data(447)) …
uint8(data(448)) uint8(data(449)) …
uint8(data(450)) uint8(data(451))];
floatPosX= typecast(dataCartPosX, ‘double’);

Thanks in advance,
Chris

2

Hi Chris,

I don’t have Matlab to test your code but could it potentially be a byte order issue? Try swapbytes?

3

Thanks for the answer.
Yes I tried this also, but it doesnt work.

4

Ok, does any of the rest of the message make sense? Like the message size or the time? Does the value change at all when you change the TCP X position? I do the same thing with the Python struct library and it seems to work.

5

Yes, it changes, but the values make no sense.