I am trying to control a digital attenuator using GPIB and VISA. I am
using viWrite to write the control string to the device. What happens
is the control message is written to the device and the attenuaton is
set, but the write operation doesn't return until it timesout. Also
after it timesout the attenuator does not respond to anymore commands and I have to power cycle it to get it to work again. The
strange thing is that if I use the VISA Interactive Control to manually
do viWrite commands to the attenuator, it works every time. It seems that Im not doing something right in my code since the viWrite in the interactive control works flawlessly.
The two functions I made to call and set the attenuator, first I call
AttenConfig to open a connection to the device, then AttenSet to set
the attenuation.
//----------------------------------------------------------------------------------------
// Function: AttenConfig
// Description: Configures and opens a connection to the digial attenuator
// Paramaters:
// Returns: int 0 for success
//----------------------------------------------------------------------------------------
int __stdcall AttenConfig(int client, void *Data){
int status = 0;
//Get session
viOpenDefaultRM(&RmViSession);
//Open device
status = viOpen(RmViSession, "GPIB::10::INSTR", VI_NULL, VI_NULL, &AttenViSession);
if(status != 0){
fpUILog("...Weinschel 8310 Driver Open Device Error");
GeneralReturn(-1, client);
}else{
GeneralReturn(0, client);
}
return 0;
}
//----------------------------------------------------------------------------------------
// Function: AttenSet
// Description: Sets the attenuator
// Paramaters:
// Returns: int 0 for success
//----------------------------------------------------------------------------------------
int __stdcall AttenSet(int client, void *Data){
int *temp, status = 0;
char Command[10];
temp = Data;
memset(Command, '\0', 10);
strcpy(Command, "ATTN ");
Fmt(&Command[strlen(Command)], "%s<%i", *temp);
status = viWrite(AttenViSession, Command, sizeof(Command), VI_NULL);
if(status != 0){
fpUILog("...Weinschel 8310 Driver Set Atten Error");
GeneralReturn(-1, client);
}else{
GeneralReturn(0, client);
}
return 0;
}
Any thoughts?
