The warning is caused by the fact that the specified DAQ device does not support clocked (hardware timed) digital operations (input or output).
Depending on the DAQ device model used, the following scenarios are possible:
1. Many NI DAQ device models do not support clocked digital I/O operations, so only software timed operations (inputSingleScan and outputSingleScan) would be available in this case.
Refer to the manufacturer-provided specifications for the specific DAQ device model/
Note the following in the specifications example for NI USB 6210:
Timing : Software in the Digital I/O section
Use a DAQ device which supports clocked (hardware timed) operations for the digital I/O subsystem. Use a separate session for channels which do not support clocked operations, for example use analog input channels grouped in one session (s1), and digital channels grouped in a separate session (s2).
2. Some NI DAQ device models have multiple digital I/O ports (groups of lines, or channels in MATLAB), with some of the ports supporting hardware-timed (clocked) digital I/O operations, but some of the ports not supporting clocked operations.
Refer to the manufacturer-provided specifications for the specific DAQ device model
For example from the specifications for NI USB 6361, it looks as though only port 0 (8 lines, P0.0 - P0.7) supports hardware-timed clocked operations, while the other two ports (16 lines, P1.0 - P1.7 and P2.0 - P 2.7) support only software-timed operations.
Note the following in the specifications example for NI USB 6361: Timing: Software, Hardware Clocked Lines: 8 Maximum Clock Rate: 1 MHz
In this case, to use clocked operations in session, add only digital channels which correspond to a port/line with support for hardware-timed operations.
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