Serial communication terminator

chocobo_ff · July 29, 2013 at 8:11 AM

I'm hoping someone can share some light to what I'm doing wrong or rather, the proper way to do serial communication on the KRC2 (software version 5.2).

On the KUKA side, this is the code I have:

Code

; Serial variables.
  OFFSET = 0 ; Data offset.
  TIMEOUT = 3.0 ; [s].
  MR_T = #ABS ; Initialise active reading.


  ; -----------------------------------
  ; Main.
  ; -----------------------------------
  ; Open serial port.
  COPEN(:SER_3, HANDLE)
  IF (HANDLE == 0) THEN
    HALT
  ENDIF


  ; Read data.
  ; Start point.
  OFFSET = 0
  CREAD(HANDLE, SR_T, MR_T, TIMEOUT, OFFSET, "%F%F%F%F%F%F", P_x, P_y, P_z, P_a, P_b, P_c) ;
  P_points[1].x = P_x ;
  P_points[1].y = P_y ;
  P_points[1].z = P_z ;
  P_points[1].a = P_a ;
  P_points[1].b = P_b ;
  P_points[1].c = P_c ;

  ; End point.
  OFFSET = 0
  CREAD(HANDLE, SR_T, MR_T, TIMEOUT, OFFSET, "%F%F%F%F%F%F", P_x, P_y, P_z, P_a, P_b, P_c) ;
  P_points[2].x = P_x ;
  P_points[2].y = P_y ;
  P_points[2].z = P_z ;
  P_points[2].a = P_a ;
  P_points[2].b = P_b ;
  P_points[2].c = P_c ;

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And I'm sending data via RS232 from MATLAB on another computer. The code is:

Code

point = [0, 100, 200, 0, 90, 0];


% Serial parameters.
s = serial(COM, 'BaudRate', 9600, 'DataBits', 8, 'StopBits', 1, ...
    'Parity', 'Even', 'FlowControl', 'Software');


% Open COM port.
fopen(s);


% Send data to KUKA.
str = sprintf('%f %f %f %f %f %f', ...
    point(1), point(2), point(3), ...
    point(4), point(5), point(6));


fprintf(s, '%s', str);


% Close COM Port.
fclose(s);
delete(s);


point = [0, 200, 200, 0, 90, 0];


% Serial parameters.
s = serial(COM, 'BaudRate', 9600, 'DataBits', 8, 'StopBits', 1, ...
    'Parity', 'Even', 'FlowControl', 'Software');


% Open COM port.
fopen(s);


% Send data to KUKA.
str = sprintf('%f %f %f %f %f %f', ...
    point(1), point(2), point(3), ...
    point(4), point(5), point(6));


fprintf(s, '%s', str);


% Close COM Port.
fclose(s);
delete(s);

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The reason I open/close the serial port on the MATLAB side for each send command is because if I don't, the data received on the KUKA side appears as one long string (from telnet), and the second read command on the KUKA side complains that there is no data available. My guess is I'm probably not applying the right terminator from the MATLAB side, but I'm not sure what to do. I've tried \r, \n, \r\n but with no luck.

The flow control is set to XONXOFF, and I've double checked all the serial settings and they match up. Sorry I am not at work right now so can't provide much more information, but if something is not clear please advise and I'll see what I can do tonight, otherwise I'll get the required information first thing tomorrow morning.

Many thanks.

**SkyeFire** · July 29, 2013 at 6:28 PM

Hm. I don't know how you go about adding ASCII control codes to strings in MatLab, but I know that in KRL, I had to do it by using hex/integer codes and a string append. The integer ASCII number for \R is 13, and the code for \N is 10. So you need a way in MatLab to insert an integer into a string "raw," without that integer undergoing ASCII string conversion. I'm sure there's a MatLab function for this.

chocobo_ff · 2013-07-30 08.10.09.jpg

SkyeFire, could you please elaborate more on how you would do it in KRL? The next thing I need to do is send command back to an external PC, and I've done some quick tests, in MATLAB It says "Unsuccessful read: A timeout occurred before the Terminator was reached" (default terminator in MATLAB is \n). The serial port is set for synchronous writing, and the data was sent by:

Code

CWRITE(HANDLE,SW_T,MW_T,”%d”,IS_VALUE) ; INT IS_VALUE, IS_VALUE = 12345

Also, going back to the reading on the KUKA side, I've tried appending \n, \r to the string from MATLAB, please see the first image for the values read by the KRC2 (output from telnet). The string shows various <0xD>, <0xA>, which I understand are \n and \r in hex form:

Code

SER[3]-RX: 0.000 ... 1.000000<0xD><0xA>0.000 ... etc ; data received in one string

What I would like the robot to see is shown in the second image, where each string is treated separately, e.g.

Code

SER[3]-RX: -510... etc
SER[3]-RX: -510... etc ; data received in two separate strings

This could be due to the way I'm sending the data in MATLAB. Is the correct terminator \r, \n or \r\n ?

chocobo_ff · July 30, 2013 at 2:06 AM

Just a quick update, I think I've solved the problem of receiving data on the KUKA side, will post what I've done bit later when I have some free time, now just need to figure out how to append terminators when sending data from the KUKA side...

**SkyeFire** · July 30, 2013 at 11:30 PM

Here's some old test code I did that involved this question:

SRC:

Code

&ACCESS RVP
&REL 237
&PARAM TEMPLATE = C:\KRC\Roboter\Template\ExpertVorgabe
&PARAM EDITMASK = *
DEF serial( )
DECL BOOL Pass
DECL INT CR, Comma1, Comma2, Comma3
DECL CHAR Comma, MiscString[50]


Pass = strclear(Result[])        ; Init receiving string
Pass = strclear (Send_Command[]) ; Init Transmission string
Pass = StrClear (MiscString[])


CR=13       ; INT ASCII value of "Carriage Return"
Comma = 44  ; INT ASCII value of a comma ","


offset=0 ; SWRITE will work from first position of string
SWRITE(Send_Command[], CH_State, Offset, "%s", VisionRequest[]) ; write command string to tx string
IF ch_State.RET1 <> #CMD_OK THEN ; check success of SWRITE
  halt  ; halt if error
ENDIF


Offset = (( StrLen (Send_Command[])) +1 ) ; find end of string
Send_command[Offset]=CR ; add [CR] to end of string


halt


COPEN (:SER_3, Handle) ; open serial port COM3


CWRITE (Handle, TX_State, Mode, "%s", Send_Command[]) ; send TX string


Mode = #ABS ; CREAD waits for data or timeout


WAIT FOR ($DATA_SER3 <> 0) ; wait for data in COM3 buffer
;wait sec 5


offset=0 ; start from string first character


CREAD (Handle, RX_State, Mode, Timeout, Offset, "%s", Result[]) ; read serial buffer into RX string


CCLOSE (Handle, CH_State) ; close serial channel


halt


Offset = 0 ; Start SREAD from first string character
SREAD (Result[], CH_State, Offset, "%2s,%10f,%10f", MiscString[], X_Result, Y_Result) ; extract X and Y values from string, MiscString serves to remove "T1,"


halt


; ================footnotes====================
; SREAD,SWRITE,CREAD,CWRITE, first string position uses Offset=0
; STRLEN, STRFIND, others, first string position is OFFSET=1, follow the same rule as an array[] variable
; Adding CR to string with SWRITE using %c doesn't work, need to research
; X and Y are both 10chars long, but need different %f sizes in SREAD to work out properly.  Need to research.


END

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DAT:

Code

&ACCESS RVP
&REL 237
&PARAM TEMPLATE = C:\KRC\Roboter\Template\ExpertVorgabe
&PARAM EDITMASK = *
DEFDAT  SERIAL PUBLIC




DECL INT Handle=3
DECL INT Offset=24
DECL REAL Timeout=5.0
DECL STATE_T TX_State={RET1 #CMD_OK,MSG_NO 0,HITS 1,LENGTH 0}
DECL STATE_T RX_State={RET1 #DATA_BLK,MSG_NO 0,HITS 1,LENGTH 37}
DECL STATE_T CH_State={RET1 #DATA_BLK,MSG_NO 0,HITS 3,LENGTH 2}
DECL MODUS_T Mode=#ABS
DECL CHAR VisionRequest[2]
VisionRequest[]="T1"
DECL CHAR Result[100]
Result[]="T1,+00205.454,+00217.879,+0000205.467"
DECL CHAR Send_Command[10]
Send_Command[]="T1'H0D'"


DECL REAL X_Result=205.453995
DECL REAL Y_Result=217.878998


ENDDAT

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chocobo_ff · July 31, 2013 at 4:08 AM

Thanks SkyeFyre, that did the trick. It does seem strange that for something so simple, the amount of work required to get it to work...

LEDdiablo · December 11, 2013 at 12:49 PM

Hy everybody!

I have a similar problem with one of my projects. I tried a lots of things, but no success. The thing is that my KRL program runs once succesfully, but when i send the same messeage in the second cycle, i get the 1550 error: No more data/variables available. I know its something so freaking simple but i just keep missing it.

Config: KR5 arc w KRC2
OS ver.: 5.5.2.
Baud 9600
data bits 8
stop bits 1
parity even
i tried Xon/Xoff and pure serial with the same results.
I communicate it with a PC via USB-serial, I handle serial comm. on the PC side with a NI Labview VI and/or Terminals

I attached my prog., pleas if somebody could take a peak in it!

**SkyeFire** · December 11, 2013 at 10:20 PM

Where exactly does it fault? During the Open, Send, Rec, or Close?

LEDdiablo · December 12, 2013 at 8:52 AM

In line 34, it's waiting for the data, but when i send a telegram it immadeitely stops with the 1550 error

LEDdiablo · December 12, 2013 at 10:48 AM

I made another program since, but i get the same error. I monitored the variables, all seems to be right, but in the CREAD line i get the 1550. I think it's my unlucky number...

I use the parameters (9600 baud, 8 bits, 1 stopbit, no parity) with no serial protocoll (on the KUKA: Xon/Xoff, the values are 0), and sending data via serial terminal. The robot gets the messeage that I send (1#013 and 2#013, which translates to 1CR and 2CR), recognises the CR (monitored the $data_ser3, i get 1 and 2). But the CREAD doesn't work...

BRIES · January 6, 2016 at 4:10 PM

Quote from chocobo_ff
Also, going back to the reading on the KUKA side, I've tried appending \n, \r to the string from MATLAB, please see the first image for the values read by the KRC2 (output from telnet). The string shows various <0xD>, <0xA>, which I understand are \n and \r in hex form:
Code
SER[3]-RX: 0.000 ... 1.000000<0xD><0xA>0.000 ... etc ; data received in one string
What I would like the robot to see is shown in the second image, where each string is treated separately, e.g.
Code
SER[3]-RX: -510... etc
SER[3]-RX: -510... etc ; data received in two separate strings
This could be due to the way I'm sending the data in MATLAB. Is the correct terminator \r, \n or \r\n ?

I apologize for bringing back an old thread but this is the exact same problem I'm having trying to receive data from Matlab. It's showing up just like the first image, where all the received data shows up as a single string with hex terminators separating them. I've tried \r, \n, \r\n, \n\r without success.
Chocobo_ff, how'd you solve this?

Thanks

Spl · January 6, 2016 at 5:00 PM

Read the data in as floats and two characters instead of a string.

BRIES · January 6, 2016 at 5:15 PM

Quote from Spl

Read the data in as floats and two characters instead of a string.

You're refering to the CREAD correct? I've tried that and it works fine if I'm only receiving one set of data, but when I receive 2 or more sets telnet shows it as: SER[3]-RX: 1.000 1.000 1.000 <0xD>2.000 2.000 2.000 <0xD>.... (<0xD> can be replaced with <0xA> or a combination of the two).
Is this the preferable way to program this: CREAD (HANDLE, SR_T, MR_T, TIMEOUT, OFFSET, "%f %f %f %1r %f %f %f %1r", x[1], y[1], z[1], CR[1], x[2], y[2], z[2], CR[2])
It would seem to be cumbersome once more data is received

[edited grammatical error]

Spl · January 6, 2016 at 5:31 PM

Yes I'm referring to the CREAD, and you should use some type of loop or interrupt to read the data in. Unfortunately I don't have an example code at me right now, since I at home, but I can post it tomorrow.

Added example codes for the serial communication from our old research project.

amila.robise · March 9, 2017 at 3:13 PM

I have started a project which is a master slave robot system with KUKA KR16 L6 robot in my university. I also having problems regarding communicating with KRC2 controller since this is my 1st time. could you please tell me the software applications from external PC side and KUKA robot side you used for communication. and how to send motor position angles to KUKA controller using an external PC...?

I also planning to use RS232 communication method.

Thanks in advance.

Serial communication terminator

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