Quantum Data 881 - Manual (Page 419)

881/882 Video Test Generator User Guide (Rev A.22) 401
CEC1:BUSM:TIME? 3 1000 // Queries buffer for the timing of bits 3
through 1000 in the buffer for CEC1
The response will be in a format that lists the low time in milliseconds followed by the
high time in milliseconds as shown below:
3.69 0.80
1.49 0.90
0.59 1.80
1.49 0.90
.
.
.
0.59 1.80
To query the bus monitor for the value of a bit in the buffer:
1. Query the bus monitor for the value of a bit in the buffer by entering the following
command:
CEC1:BUSM:BITV? -4 // Queries CEC1 buffer for value of the bit that
occurred 4 bits ago.
CEC1:BUSM:BITV? 20 // Queries CEC1 buffer for the 20th bit in the
buffer
The response will be in the format
-1 - index does not exist or the bit was corrupted
0 - index is a logical zero data bit
1 - index is a logical one data bit
2 - index is a start data bit
3 - index corresponds to an idle period only (no data)
4 - index corresponds to an error signal (sent after a corrupted bit)
To query a message for the byte number of the end of message:
1. Query a message in the bus monitor for the end of message byte:
CEC1:BUSM:EOMB? -3 // Queries message in CEC1 buffer that occurred
3 messages ago
7 // Indicates that the EOM byte was the 7th in
the message queried
CEC1:BUSM:EOMB? 4 // Queries the 4th message in CEC1 buffer for EOM
byte
5 // Indicates that the EOM byte was the 5th in
the message queried
To query a message for the polarity of the acknowledge bits:
1. Query a message in the bus monitor for the polarity of the acknowledge bits in a specific
message:
CEC1:BUSM:ACKV? -3 // Queries message in CEC1 buffer that occurred
3 messages ago for polarity of ack bits