RPT 301 User Manual 11
K177 Issue No. 3
3 Operation

3.1 System Operation

The frequency output from the sensor is counted for a fixed number of
cycles. A mid-scale pressure gives a measurement period of
approximately 0.5 seconds. During this time a high frequency clock is
also being counted and at the end of the measuring cycle it is this value
which is transferred to the processor for conversion into its pressure
equivalent.
Measurement cycles are continuous, unless specifically interrupted
(see the G command). Each cycle delivers a new pressure value to the
programmable filter. The output of this filter is stored in a buffer and
may be requested by the control computer or sent automatically at a
programmable interval to the control computer.

3.2 Command Summary

The instrument has a range of commands summarised in the table and
detailed in this section. Some of these commands generate a reply
from the instrument, the general format of these replies is given in
section 3.4.