NI-Serial 21.5 Bug Fixes


The following items are notable issues fixed between the release of NI-Serial 21.3 and NI-Serial 21.5, including additional patches and service packs. If you have an issue ID, you can search this list to validate that the issue has been fixed. This is not an exhaustive list of issues fixed in the current version of NI-Serial.

Bug Number

Legacy ID




Reading and writing single-byte messages at a high rate to a large number of ports on Linux RT might drop data

When writing and reading 1-byte messages between NI-Serial ports on NI Linux RT, read operations have been observed, in rare cases, to fail to read all written data when writing to large numbers of ports (more than 16) at high rates.


There is currently no known workaround for this issue.

Reported Version:

NI-Serial 21.3

Resolved Version:

NI-Serial 21.5


Oct 20, 2021

Additional Patch Information

Installing some patches may require certain additional steps or considerations. Please refer to the following table for more information about patches for this release.

These patches currently do not have any special instructions.

Glossary of Terms


  • Bug ID - When an issue is reported to NI, you may be given this ID or find it on  You may also find IDs posted by NI on the discussion forums or in KnowledgeBase articles.
  • Legacy ID – An older issue ID that refers to the same issue.  You may instead find this issue ID in older known issues documents.
  • Description - A few sentences which describe the problem. The brief description given does not necessarily describe the problem in full detail.
  • Workaround - Possible ways to work around the problem.
  • Reported Version - The earliest version in which the issue was reported.
  • Resolved Version - Version in which the issue was resolved or was no longer applicable. "N/A" indicates that the issue has not been resolved.
  • Date Added - The date the issue was added to the document (not the reported date).