Teledyne LeCroy SierraFC M8-4 User Manual - Manual (Page 243)

SierraFC M8‐4 Protocol Analyzer User Manual 243
Software Settings Teledyne LeCroy
Here are examples of different Port Configurations and Trigger Positions:
 One port configuration (A ‐ ‐ ‐): Sample size is user‐specified sample size.
 Two port configuration (AA ‐ ‐): Ports 1 and 2 are on the same FPGA, so
Memory Assignment has an effect. If you use snapshot triggering, the sample
size is near specified size.
 Two port configuration (AA ‐ ‐): If you use manual stop, Memory Assignment has
no effect. Sample size depends on port traffic loads.
 Two port configuration (AA ‐ ‐): If trigger is set at 50%, and there is enough data
to fill pre‐trigger, Memory Assignment has an effect. Sample size is typically near
specified size.
 Two port configuration (AA ‐ ‐): If trigger is set at 50%, but there is not enough
data to fill pre‐trigger, Memory Assignment has an effect. Sample size is typically
more than half specified size, with size determined by the amount of data cap‐
tured before trigger.
 Two port configuration (A ‐ A ‐): Ports 1 and 3 are not on the same FPGA, so
Memory Assignment has no effect. If one port has heavy traffic, it may fill its
memory bank and stop recording, resulting in smaller sample size than specified.
NOTE 1: Checking this option does not affect the sample. It only allows larger sample
sizes.
NOTE 2: If traffic is balanced on ports, sample size is the same whether you check or
uncheck the Sampling Memory Usage Optimization option.
NOTE 3: Memory Assignment depends on traffic load distribution at the time when the
system tries to re‐assign physical links to memory banks. Therefore, if you repeat a
capture with the same Sampling Memory Size and Segment Number parameters, the
resulting sample size may not be the same. However, if traffic load distribution is similar,
sample size will be similar.
NOTE 4: The buffer status indicator shows buffer by FPGA, not by port.
If the Sampling Memory Usage Optimization Option is Not Checked
Each physical link (or logical link if MUX is enabled) is assigned to a specific memory space
(memory bank), depending on the Sampling Memory Size and Segment Number
parameters.
Important: If any physical link fills its memory bank, the recording process stops. Other
memory banks will typically be less than full (and can be empty). The sample file might be
smaller than the user‐defined Sampling Memory Size. You might even think that the
Analyzer malfunctioned.