Technical data

of the Skip Ordered Set (SKPOS) primitives. The change in the SKPOS length by
DUT is to compensate for the speed differences of the clock domains. DUT/Slave
receives SKP Ordered Set of 16 symbol and if clock compensation is required, DUT
must add or remove four skip symbols per Skip Ordered Set. Hence received Skip
Ordered Set can be 8, 12, 16, 20, or 24 Symbols. The SKP_END Symbol indicates
the last four Symbols of SKP Ordered Set. The three Symbols received after
loopback following the SKP_END Symbol can be different. Although bit-wise
different in content and number of bits, in order to report this different looped back
bit stream as error free the ED has to recognize the different length SKPOS and
ignore these symbols.
You need to set the respective error ratio mode from the J-BERT's error detector
(ED) window. See the User Guide for the complete description on how to set up
the error ratio.
N O T E
"PCIe" and "PCI Express" are the registered trademarks of the PCI-SIG.
Working with PCIe3 SKPOS – Procedures
The following code indicates how you could set up and evaluate the PCIe3 SKPOS
results using SCPI.
How to Set PCIe3 SKPOS Mode
The following command sets the PCIe3 SKPOS mode:
SENSe[1]:ERMode:MODe PCI3BER
How to Evaluate SKPOS Count Results
You can use the following queries to evaluate SKPOS count results:
1
The following query returns total number of SKPOS bit received in a time
interval.
[P]FETCh[:SENSe[1]]:FSCount[:ALL][:FULL][:TOTal]?
2
The following query returns the “Instantaneous” number of SKPOS bits,
calculated from the counts obtained in the last deci- second. This value is
available even when accumulation is turned off.
[P]FETCh[:SENSe[1]]:FSCount[:ALL][:FULL]:DELTa?
3
The following query returns the ratio of the number of SKPOS bits to the number
of bits received in the current (or last completed) accumulation period, specified
by the gate period.
3 Recommended Programming Techniques
76 Agilent J-BERT N4903B High-Performance Serial BERT