Can create DAQmxCreateDIChan and DAQmxCreateDOChan in the same task.

[KengThailand]

Hi,

       Can we create DI and DO channel in the same task? Below is my coding but if used the same task it show error message.

         Error Msg  = 

Task cannot contain a channel with the specified channel type, because the task already contains channels with a different channel type.

Create one task for each channel type.

Code =

' Create the DAQmx task.
DAQmxErrChk DAQmxCreateTask("", vTaskHwnd)
' Add a digital input channel to the task.
DAQmxErrChk DAQmxCreateDIChan(vTaskHwnd, DIPortAddress, "", DAQmx_Val_ChanForAllLines)
DAQmxErrChk DAQmxCreateDOChan(vTaskHwnd, DOPortAddress, "", DAQmx_Val_ChanForAllLines)
'Start the task running, and read from the digital lines.
DAQmxErrChk DAQmxStartTask(vTaskHwnd)

vTaskIsRunning = True

Thank you very much.

[ben64]

The error message already answered your question: no you can't have DI and DO channels in the same task.

Ben64

[Curt_C]

Hi,

Just use the same task to write and read.

using (Task digitalWriteTask = new Task())
                {
                    //  Create an Digital Output channel and name it.
                    digitalWriteTask.DOChannels.CreateChannel("Dev1/po​rt0", "port0",
                        ChannelLineGrouping.OneChannelForAllLines);

                    //  Write digital port data. WriteDigitalSingChanSingSampPort writes a single sample
                    //  of digital data on demand, so no timeout is necessary.
                    DigitalSingleChannelWriter writer = new DigitalSingleChannelWriter(digitalWriteTask.Stream​);
                    writer.WriteSingleSamplePort(true, (UInt16)this.numericEdit1.Value  );

                    //  Create the reader
                    DigitalSingleChannelReader reader = new DigitalSingleChannelReader(digitalWriteTask.Stream​);
                    //   Read back the value
                    this.textBox1.Text =  reader.ReadSingleSamplePortByte().ToString();


                }

Curt

[PeterHodges]

No you can't.

[Curt_C]

Yes you can. It works!

Curt

[ben64]

---

@Curt_C wrote:

Yes you can. It works!

Curt

---

The answer is no you can't. Curt I agree that your code work but it is not the same thing. Your task only have DO channels that outputs data to a stream. Your reader is reading data from this stream so it is more like an echo mode, it is not reading input data from a physical channel.

Ben64