Calling external dll problem (comunication with pressure sensor using KELLER Druckmesstechnik dll driver )

[lukaszsz]

Hi ;

I’m building  application for data acquisition in my university project (pressure measurement) using external DLL library  to communicating with device .

So far , I had no problem with calling function available from DLL . But when I tried to call function for  read out of  pressure value , unexpected  error  appeared  , and All my ideas to solve this problem  failed , and maybe some of You had similar problem in the past:

I’m using “Call Library Function”  to execute function from DLL . The DLL (s30c.dll ) is a library for communication with intelligent pressure senor (KELLER

Druckmesstechnik  pressure sensor with converter RS232-RS485  K-107  (modbus communication , http://www.kelleramerica.com/manuals-and-software/manuals/Comm_Protocol_Series_30_V2.2.pdf )

 In general , the call convention stdcall is used for assigning the parameters to the functions (-  all parameters are passed via the stack, -  the parameter furthest to the right is calculated and passed first, the parameter furthest to the left is calculated and passed last, -  the function itself deletes the parameters from the stack.)

I have connected  and called successful  function for  read serial No , Configuration of pressure sensor . But when I try to call read out pressure  function the unexpected faults occur.

When   input parameters are being read by Call Library Function block the  Labview application stops  and  Message box  about error appears (information that unexpected error appeared and application should be restarted ).

But it is only when I use correct device address ( 255  (Byte : 8-bit without sign) also when I use Communication address ( 250 )  the application stopped. But  then I write incorrect address (for example 251) the function receive  RS_TIMEOUT status , when I disconnect line data to address input the function receive : BROADCAST info . 

So it is mean that Call Library Function block  are configured properly .

In Call Library Function we can configure  type of input parameters as  void type, and when a use this option for address input for  250 or 255 address , the function receive  RS_TIMEOUT status.

I thought that problem is in type of address ( format 8-bit without sign ) , but for incorrect address for properly format input data function receive   information (RS_TIMEOUT ) . I also thought that function has problem with pressure data receive (32 bit frame (floating poing)) but in this case function shoult receive info : “Function successfully executed; but exception error  has occurred.

Im sure that application stops when input data (address) are reading by Call Library Function  , but I can’t  identify problem why it is stoppinng..

Have You ever  used  this device ( DLL driver for data  acquisition ) , and had similar problems?

.For any ideas I would be very grateful.

[Gregor Cerne]

Hello,

From this description I can't tell you what the problem is - please narrow the problem to 1 of those 3 areas:

- hardware malfunction

- communication problems

- dll library

To do that, test each part seperately - check hardware if it is working properly,then try to communicate with device through some other program, and check if there is no errors in the dll library

Best Regards,

Gregor Cerne

National Instruments

[lukaszsz]

Hi;

thanks for reply.

I have resolved problem . Function specified in DLL  which I'm using in application  I called successfully. I had problem with  only one function (reading data from device) , but I wrote (build) Vis based on communication protocol of sensor to reading data.

Best regards   

[Gregor Cerne]

Hello,

I'm glad that you resolved your problem. If your will encounter any more problems, feel free to ask.

Best regards,

Gregor Cerne

National Instruments

[DanielRoth]

I do have the same Problems ... if you are using LV VISA Drivers, please place your CODE-Sample here

THANKS

[matbeg]

Hi lukaszsz,

I know it's been a long time since you posted here but as I am trying to write my own Vi, could you please help me by showing it to me ?

I have been receiving an answer from the sensor with the frame described in the Communication Protocol but it is not as it should be...

Capture.jpg shows the sent and received message and Capture2.jpg shows how I built the blocks.

Thank you in advance for your answer.

Best regards,