HRW HPD0440BNMR V401 Manual 111116.doc E. & O. E. / Subject to change without notice Page 29 of 43
Using a point type 5 or 6 will generate two sequential data points with in the MR table of either F03 or
F04 respectively for registers using IEEE floating-point data format which are always 2 Word registers.
The first point address is entered in the point configuration string and the second point is automatically
generated. These two points are then always read together when the Modbus network is polled.
Using a point type 7 or 8 will generate two data points with in the MR table of either F03 or F04
respectively for registers which are 2 Word integers (typically energy registers in electricity meters). The
first point address is entered in the point configuration string and the second point is automatically
generated. If a register is more than 2 Words then additional single or pair points can be added
sequentially. In any case, the value result of multiple Word points may be compiled and represented by
the first point in the sequence using the Scaling feature as described later.
When point pairs are generated (types 5…8) the first of the pair has a normal type tag, such as RHR,
whereas the second of the pair has a ‘P’ tag suffix, for instance RHR
P
(
P
aired with the preceding point).
Each point may be individually scaled and/or combined with sequential points where Modbus registers
are comprised of more than 1 Word and therefore use more than one MR point. This is helpful when, for
example, the 1
st
Word of a register may be units and the 2
nd
Word may require a multiplier of 65,536 or
some other scaling before combining with the 1
st
Word.
In any case where two or more Words are combined then only the first MR point (object) of the
sequence of Words needs be read up by the BMS as this first point of the sequence contains the final
result of the scaling and combining.
Scaling types may be viewed in HyperTerminal by entering
MRS
to display the scaling table:
Scaling types may be assigned to an MR point either as a part of the Point Programming string or
individually after initial point configuration. To scale an individual point as being x10 then a Scale type
value of
7
must be assigned to that point, as referenced in the left-hand column of the table above. If
the next sequential point is to be combined with a point value then the scaling type value +100
configures the point to add the result of the next sequential point. For instance:
An eight digit Wh register with value 12,345,678 Wh comprised of 2 Words needs the MR 2 Word points
to be combined to represent the register value of 12,345.678 kW at one only BACnet AV Object. The 1
st
Word is configured at MR point 153 (with value 5678) and the 2
nd
Word is configured sequentially at
point 154 (with value 1234).
