Quantum Data 881 - Manual (Page 408)

390 Chapter 11 CEC Interactive Troubleshooting Environment (ITE)
The condition of incorrect acknowledgement will remain in place until you reset it.
Therefore once activated the improper acknowledgement remains for all messages
received by the 882.
To test message acknowledgement:
1. Enter the following command to simulate a message acknowledgement error.
CEC1:CECT:NACK 1 0 0 0 //indicates a directed header block will not
be acknowledged
CEC1:CECT:NACK 0 0 0 1
//indicates a broadcast data block will not be
acknowledged