Beluk BLR-CM Modbus, Техническая документация инструкция

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Technical Documentation
BLR-CM Modbus Rev. 05
2018-09
11
The data can be of the following types:

FLOAT: 32 bit floating-point number, as it is defined in IEEE-754.

UINT16: Unsigned 16 bit integer value.

UINT32, SINT32: Unsigned/signed 32 bit integer value.
Since the data is organized in 16 bit wide words, a set of sequential addresses has to be read in order to get longer data
items. In this case, only the base address is given in the tables. For example, to read a FLOAT value with base address
12, two 16 bit words must be read (addresses 12 and 13). These two values need to be concatenated to form the desired
result of 32 bits. Most SCADA software packages or PLCs can do this automatically.
There exist different types of addresses:

The Modbus address always starts with 0 and can go up to 65535. It can be used with any
function code.

Certain PLCs cannot handle the address 0 and therefore add 1 to the address. So their
addresses system (Modbus a1) always start with 1.

Some SCADA tools add an offset to determine the function code, which is used to access the
device at the given address. Sometimes, they also add 1 to the Modbus address.
As an example, the address 40001 would be “read Modbus address 0 with function code
03
hex
”, 30012 would be “read Modbus address 11 with function code 04
hex
”.
Please refer to the corresponding software’s manual to find the correct addresses.
Attention: The following tables always give the Modbus addresses mentioned first in above list.
3.3 Measurement values
The measured values are available in an interval of 2 data words, starting at address 0. All values can be accessed with
function codes 03
hex
and 04
hex.
.
If the current or voltage is too small to calculate valid harmonics, the value at the base address (= the fundamental) is
0.0%. This also indicates, that the higher harmonic current or voltage values are also invalid!
Attention: The values Apparent power sum, Active power sum, Reactive power sum, Lacking reactive power ΔQ and
Power factor (P/S) refere to a symmetrical power system.
!