National Instruments NI-VXI - Manual (Page 139)

Glossary
NI-VXI User Manual G-16 © National Instruments Corporation
WRviol Write Ready protocol violation; a type of Word Serial Protocol error.
If a Commander attempts to write a command or query to a Servant
that is not Write Ready (already has a command or query pending), a
Write Ready protocol violation may be generated.
WSP See Word Serial Protocol