Hi everybody, I'm writing an application that controls robot arm and I need Your assistance. Long story short robot arm is controller with telnet session. I was able to successfully connect to it using Code: #import <CoreFoundation/CFSocket.h> and send defined commands like this: Code: UInt8 message = "do home\r\n"; //returns arm to home possition CFDataRef data = CFDataCreate(NULL, message, sizeof(message)); CFSocketSendData(s, NULL, data, 0); CFRelease(data); but as the application develops I'm trying to put variables into sanded commands, i.e.: Code: do drive 1,20 do drive 2,45 do drive 4,-10 I approached this challenge by defining my command as NSString: Code: int joint=1, value=45; command = [NSString stringWithFormat: @"do drive %d,%d\r\n",joint,value]; and I'm trying to covert my command (NSString) to message format (UInt8 array) so it can be sanded the like before. After couple of hours googleing and searching through forum I came to realize that I cant do it alone and I need help. Any advice is greatly appreciated.