Campbell Scientific PWS100 Present Weather Sensor - Manual (Page 22)

Section 5. Specifications
5-4
The particle buffer is able to hold raw data for 500 typical particles. The
processor is able to process the particles at a rate of 120 particles per second,
typically. This means if more than 120 particles per second fall through the
sample volume of 40 cm
2 the particle buffer will start to fill up. If the rain rate
exceeds 120 particles per second for a prolonged period, the buffer could run
out of space and particles will be lost.
The fact that the processor is running behind real-time and/or particles are
being missed can be monitored in the alarm message which can be selected for
data output.
The particle processor then places data about each particle in the Large Particle
Array (LPA). The LPA is 100000 records long. It uses 5 records every 10
seconds plus a record for every processed particle that passes through the
volume. For example if 20 particles per second are processed then 20.5 records
are used per second. Since 100000 records can be stored, the system can store
100000 / 20.5 = 4878 seconds worth of data in the LPA. The user needs to be
aware of the size of this buffer as it is used to hold data that is processed when
a message is output. The size of the buffer may become a limiting factor if a
very long message interval is selected and rainfall rates are high.
The PWS100 has the capability to store measured data in a buffer called the
message storage buffer, which is 1 MB (1000000 characters) in size. All ASCII
characters including CrLf must be included in any storage calculations. This
buffer stores the user defined messages (see Section 7.5, Message Related
Commands for the types of messages available to the user). A typical message
containing 120 characters can be stored 1000000 / 120 = 8333 times which at
minute intervals for the data output would be over 138 hours worth of storage.