Can I Individually Control Each Analog Output Channel on my E-Series Board?Hardware: Multifunction DAQ (MIO)
Problem: I have an E-Series board with multiple analog outputs. I would like to be able to output two independent, analog waveforms and be able to programmatically control the configuration of each channel and when each output starts/stops. Currently, I can only get my first channel configured properly before getting an error on the configuration of the second channel. How do I do this? Solution: There are two factors that make controlling two output channels impossible. First, E-series boards rely on the DAQ-STC chip to provide the timing for the board. In the E-series devices only one Analog Output update clock exists to control the timing of the analog outputs. What this means is that when you start the output on Channel 0, then the update clock, for both channels, is started, and there is not a second update clock available to control the start of the second channel independently. Second, there is a limitation in the NI-DAQ drivers that only allow you to configure one output group. Therefore you can only specify properties for one group and all channels that you wish to use must be in that one group. Using a small workaround, it is possible to output known data sets on two analog output channels and have them start at separate times. To do this, interleave the two waveforms and have them configured together and started at the same time. In order to simulate starting Channel 1 at a later time, you can then pad the interleaved array with zeros for that channel. This allows you to control your program from the front panel and in some instances may provide the necessary solution. However, even the workaround described above may not provide you with all the control and freedom over the channels that you want. The only way to achieve total control is to split up the two output channels between two separate E-series boards. Related Links: KnowledgeBase 1ATID9X4 - Configuring Separate Groups for Analog Output Channels using ComponentWorks (AT-AO-6/10 Hardware) Attachments:
Report Date: 10/15/2003 Last Updated: 07/06/2004 Document ID: 32EERVKD |
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