Error injection and the reporting of errors on the bus is one of the more confusing (and often misunderstood) aspects of the 1553 bus. The purpose of this document is to explain how we do error injection with BusTools/1553 and to explain why the bus monitor reports what it does for various error conditions. The examples shown in this document were done with BusTools/1553 version 6.40 on a PCCARD-D1553 board. A Tektronix TDS1012 oscilloscope was used to view the messages and words on the bus. Application Note 003 explains how to use an oscilloscope with the 1553 bus. This Application Note assumes a basic knowledge of 1553. For information on the MIL-STD-1553 protocol refer to the “MIL-STD-1553 Tutorial” document available from Condor Engineering Inc. Additional information can also be found in MIL-HDBK-1553A.