Multifunction DAQ
Counting analog output update events using counters in text-based NIDAQmx
I have a time analog output task, and I would like to be able to count the number of output updates so that I can send a particular digital signal high immediately after the last update. In traditional NIDAQ, I have found that I need to use two counters to accomplish this task.
In traditional NIDAQ, I wired the ao UPDATE signal to CTR0 input, and the CTR0 output, which is set up to send a pulse on reaching TC, to the input of CTR1. In my working traditional NIDAQ code, I routed the signals using SELECT_SIGNAL. My translation of this code into NIDAQmx is given below, but I think the routing part is incorrect, i.e., I need to know how to wire the UPDATE output to the CTR0 input, and the CTR0 output to the CTR1 input. I would also like to know if it is possible to reset the count of each counter to 0 without stopping and restarting the task.
Thanks in advance for your help!
(The traditional nidaq code are the statements that are commented out that begin with status=)
procedure Set_timers;
var
CTR0Channel,
CTR1Channel : PChar;
TriggerString,
TerminalString Char;
begin
//General purpose counter 0
//This counter is used to count the number of update clicks from the dacs
//First create a task handle
status:=DAQmxCreateTask('', @CTR0TaskHandle);
//Next create a CTR channel to count edges, setting the initial count to 0
StrPCopy(CTR0Channel, BoardIdentifier+'/ctr0');
status:=DAQmxCreateCICountEdgesChan(CTR0TaskHandle,
CTR0Channel, //Counter number
'', //default virtual name to assign
DAQmx_Val_Falling, //count on falling edge
0, //initial count
DAQmx_Val_CountDirection1_CountUp); // count direction
//Reset the counter
//Not sure if the next line is already taken care of above
// status:=GPCTR_Control(deviceNumber, ND_COUNTER_0, ND_RESET);
//Application is simple event counting ************ ALREADY DONE ABOVE !!
// status:=GPCTR_Set_Application(deviceNumber, ND_COUNTER_0, ND_SIMPLE_EVENT_CNT);
//Set the initial count to 0 ************ ALREADY DONE ABOVE !!
// status:=GPCTR_Change_Parameter(deviceNumber, ND_COUNTER_0, ND_INITIAL_COUNT, 0);
//Use the UPDATE* signal from the dacs on the PFI_5 pin
StrPCopy(TriggerString,'/'+BoardIdentifier+'/ao/SampleClock'); //may want to change this to PFI5
StrPCopy(TerminalString, '/'+BoardIdentifier+'Ctr0Source');
status:=DAQmxConnectTerms(TriggerString, TerminalString, DAQmx_Val_DoNotInvertPolarity);
//the lines abopve replaced the lines below
//status:=GPCTR_Change_Parameter(deviceNumber, ND_COUNTER_0, ND_SOURCE,ND_PFI_5);
//ALREADY TAKEN CARE OF ABOVE
// status:=GPCTR_Change_Parameter(deviceNumber, ND_COUNTER_0, ND_SOURCE_POLARITY, ND_HIGH_TO_LOW);
//Output pulses on reaching TC
status:=DAQmxSetExportedCtrOutEventOutputBehavior(CTR0TaskHandle,DAQmx_Val_ExportActions2_Pulse);
//line above replaced the line below
// status:=GPCTR_Change_Parameter(deviceNumber, ND_COUNTER_0, ND_OUTPUT_MODE, ND_PULSE);
//Arm the counter, ready to start when the waveform output starts
//Will do this at the end for both counters
// status:=GPCTR_Control(deviceNumber, ND_COUNTER_0, ND_PROGRAM);
{counter number 1. This counter is hooked up to counter 0, and it counts
how many times the other counter has turned over}
//First create a task handle
status:=DAQmxCreateTask('', @CTR1TaskHandle);
StrPCopy(CTR1Channel, BoardIdentifier+'/ctr1');
status:=DAQmxCreateCICountEdgesChan(CTR1TaskHandle,
CTR1Channel, //Counter number
'', //default virtual name to assign
DAQmx_Val_Rising, //count on falling edge
0, //initial count
DAQmx_Val_CountDirection1_CountUp); // count direction
//Reset the counter
// status:=GPCTR_Control(deviceNumber, ND_COUNTER_1, ND_RESET);
//Application is simple event counting
// status:=GPCTR_Set_Application(deviceNumber, ND_COUNTER_1, ND_SIMPLE_EVENT_CNT);
//Set the initial count to 0
// status:=GPCTR_Change_Parameter(deviceNumber, ND_COUNTER_1, ND_INITIAL_COUNT, 0);
//Use TC output of the first counter
StrPCopy(TriggerString,'/'+BoardIdentifier+'Ctr0Out'); //may want to change this to PFI5
StrPCopy(TerminalString, '/'+BoardIdentifier+'Ctr1Source');
status:=DAQmxConnectTerms(TriggerString, TerminalString, DAQmx_Val_DoNotInvertPolarity);
//The above lines replaced the line below
// status:=GPCTR_Change_Parameter(deviceNumber, ND_COUNTER_1, ND_SOURCE, ND_OTHER_GPCTR_TC);
//Line below is taken care of above by DAQmx_Val_Rising
// status:=GPCTR_Change_Parameter(deviceNumber, ND_COUNTER_1, ND_SOURCE_POLARITY, ND_LOW_TO_HIGH);
//Arm the counter, ready to start when the waveform output starts
// status:=GPCTR_Control(deviceNumber, ND_COUNTER_1, ND_PROGRAM);
//Start both counter tasks
status:=DAQmxStartTask(CTR0TaskHandle);
status:=DAQmxStartTask(CTR1TaskHandle);
end;
