PM[B]sense
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V1.3
4
CONFIGURATION AND MEASUREMENT
The configuration of the instrument and the reading of the measurements can be done
via the RS485 serial output, both with the proprietary protocol and with the MODBUS-
RTU protocol.
In the first 10 seconds after the instrument power on, it is always active the proprie-
tary protocol. After 10 seconds from power on, the operating protocol is activated,
which by default is the MODBUS-RTU protocol.
It is possible to keep the proprietary protocol active even after 10 seconds from power on
by sending, before the 10 seconds expire, the command
@
of the proprietary protocol.
The proprietary protocol can be set as operating protocol by means of the DP0 command.
The commands of the proprietary protocol and the registers of the MODBUS-RTU pro-
tocol are described in detail in the following chapters.
Particulate Matter measurement modes:
The transmitter can perform the PM measurement in continuous mode or, in order to
extend the sensor lifetime, at cyclic intervals (default).
In the measurement mode at cyclic intervals, the PM sensor is activated periodically
for the ON time. The measurement is made available after 70 seconds from sensor ac-
tivation (warm-up time). At the end of the ON time, the measurement is "frozen" and
the sensor is deactivated until the set cyclic measurement interval expires.
Fig. 4.1: Measurement mode at cyclic intervals
The measurement mode, the cycle interval and the sensor ON time can be configured
respectively by using the CPLS, CPLP and CPLO commands of the proprietary protocol
or the holding registers with address 15, 16 and 18 of the MODBUS-RTU protocol.
The transmitter provides three types of measurements:
•
average over a 10 seconds interval, updated every second;
•
average over a 60 seconds interval, updated every 10 seconds;
•
average over a 15 min interval, updated every minute.
For the measurement mode at cyclic intervals, the cycle interval and the ON time
must be set consistently with the desired averaging interval.
Status of the transmitter:
There are two LEDs on the internal electronic board of the transmitter: the
green
LED
indicates the presence of the external power supply (blinks once per second), the
red
LED indicates the presence of any measurement errors (normally off, it blinks twice
per second if at least one of the measured parameters is in error).
ON time
Cycle interval
Sensor ON
Sensor OFF
Summary of Contents for PMBsense-A
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