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Error -200563 or -200878 at DAQmx Read With Digital Input Channel

Updated Feb 20, 2024

Reported In

Hardware

  • C Series Digital Input Device

Software

  • LabVIEW

Driver

  • NI-DAQmx

Issue Details

  • I receive error -200563 whenever I use the DAQmx Read U8 or DAQmx Read U16 VIs on my digital input task. My task consists of less than 8 lines, so why does this error occur?
  • Whenever I configure a digital input task to read 1 port consisting of 8 lines, error -200878 reports that the Minimum Read Size (In Bits) is 32. Why is this the case?
  • How do I resolve the errors shown below when reading in U8 or U16 format for my digital input task?

Error -200563 occurred at <VI name>

Possible reason(s):
Specified digital channel contains more bits than supported by the 8-bit version of DAQmx Port Read.
Use a version of DAQmx Port Read that supports wider digital ports.

Minimum Read Size (In Bits): 32
error 200563.PNG

Error -200878 occurred at <VI name>

Possible reason(s):
Specified digital channel contains more bits than supported by the 16-bit version of DAQmx Port Read.
Use a version of DAQmx Port Read that supports wider digital ports.

Minimum Read Size (In Bits): 32

error 200878.PNG

Solution

These errors can occur when the type of C Series module is not suitable for the task configuration, or the number of lines in the task does not conform to DAQmx rules.

When configuring a DAQmx task to read digital data, the 32-bit format must be used if:
  • You have more than one 8-line port.
  • You have a port with more than 8 lines in any channel within the task.
  • You use a serial digital I/O module.
To verify whether your module is serial or parallel, refer to Digital I/O Considerations for C Series and TestScale Devices.
If using a parallel module, ensure that the read format obeys the rules explained in NI-DAQmx: Digital Data (Integer Format).

Additional Information

Most serial C Series digital I/O modules consist of more than 8 lines per port. For a parallel module, the maximum number of lines per port is always 8. As explained in Digital Data (Integer Format) - NI-DAQmx, 8-bit and 16-bit formats can only be used if there are 8 (or less) lines in the port of your largest channel.

The U8 (port format), U16 (port format) and U32 (port format) DAQmx Read VIs shown below read all lines provided by the port. Therefore, when using a serial digital I/O module, DAQmx will recognise that a module which may contain more than 8 lines per port is in use, and an error occurs.

DAQmx port format.png
If it is necessary to read less than the maximum number of lines supported by the module, use the DAQmx 1D Boolean (N Lines) VI.
 

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