Hydronix Hydro-View HV02, Руководство пользователя

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HYDRO-VIEW USER GUIDE
D0022
REV 1.06
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Grouping channels
In some situations and particularly in high-throughput batch plants, it is necessary to
measure the moisture content at several points simultaneously and provide an average
value. The Hydro-View provides a convenient way of doing this by making use of its serial
ports.
If the RS232 port is otherwise unused, then the output of two sensors can be averaged by
simply connecting the RS232 ports of two Hydro-View units together using a cross-over
cable (available from Hydronix).
The optional RS485 port can be used to provide an average of up to four sensors, which
should satisfy most application requirements.
Grouping is achieved by defining one of the Hydro-View units (it does not matter which
when using the RS232 interface) as a MASTER station with the other unit(s) as ASCII
Hex devices. See examples later for clarification.
The results of the grouping operation can be made available to external systems using
either the analogue output port or the second serial port set for
data log
or
batch print
use.
When grouping channels in this way, you must pay particular attention to calibration and
in particular do not assume that the material flowing from one gate has the same moisture
content as the others - they can be widely different at any instant. You should always aim
to take a sample from the flow of a single sensor where possible.
Group moisture variables
The channel grouping facility results in the generation of three additional moisture
variables in the system. These are referred to as...
Group M1
The average value of the NOW variables across all grouped units. This
might be used in a large batch or continuous mixing application where
there is some advantage in measuring the moisture at several points.
Group M2
The average value of the NOW variables across all grouped units which
are currently in an ‘averaging’ state i.e. the average/hold input is ON
and the average/hold delay timer has expired.
This variable would normally be used by a batch computer performing
its own time averaging.
Group
Average
The integration over time of the Group M2 value, divided by time since
the start of an averaging period. This variable will be used in the
majority of grouped applications and in general is not the same as the
average of the individual unit average values since the Group M2 value
observes the ‘averaging’ state of individual units.
The group variables automatically ignore channels which are either in an alarm condition
and/or have a low level of material (as determined by the optional level sensing inputs).
Group moisture display
When a Hydro-View unit is configured as a MASTER station, you can view the group
moisture variables by pressing the right hand soft-key when the standard moisture display
is shown. This key will ‘toggle’ between the standard display, showing the moisture
variables local to the unit, and the group display, showing the results of the grouping
operation.
Indicators to the right of the group display show which slave stations are currently
responding to communications requests from the master station.