Modbus Rtu Protocol; Modbus Memory Map - Circutor CVM-MINI SERIES Instruction Manual

6 MODBUS RTU PROTOCOL

The CVM-MINI power analyzer communicates using the MODBUS© protocol. In the
MODBUS protocol the RTU (Remote terminal Unit) mode is used; each 8-bit per byte
in a message contains two 4-bits hexadecimal characters.
The format for each byte in RTU mode is:
Code
Bits per byte
Field Check-Error
Modbus functions used:
Function 01
Function 03 and 04
Function 05

6.1 MODBUS memory map

PARAMETER
Voltage phase
Current
Active power
Reactive power
Apparent power
Power factor
Voltage phase
Current
Active power
Reactive power
Apparent power
Power factor
Voltage phase
Current
Active power
Reactive power
Apparent power
Power factor
Temperature
8 bit binary, hexadecimal 0-9, A-F.
2 hexadecimal characters contained in each 8-bit field in
the message.
8 data bits.
CRC Type (Cyclical Redundancy Check).
Reading the status of the relays.
Reading n Words (16 bits-2 bytes). Function used for
reading the electrical parameters that the CVM-MINI is
measuring. All electrical parameters are long with 32 bits,
because of this two Words are required to request each
parameter.
(4 bytes - XX XX XX XX)
Writing a relay.
SYMBOL Instant
V L1 00-01
A L1 02-03
kW L1 04-05
Kvar L1 06-07
kV·A L1 4A-4B
PF L1 08-09
V L2 0A-0B
A L2 0C-0D
kW L2 0E-0F
Kvar L2 10-11
kV·A L2 4C-4D
PF L2 12-13
V L3 14-15
A L3 16-17
kW L3 18-19
Kvar L3 1A-1B
kV·A L3 4E-4F
PF L3 1C-1D
ºC 50-51
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Maximum Minimum
60-61 C0-C1
62-63 C2-C3
64-65 C4-C5
66-67 C6-C7
AA-AB 10A-10B
68-69 C8-C9
6A-6B CA-CB
6C-6D CC-CD
6E-6F CE-CF
70-71 D0-D1
AC-AD 10C-10D
72-73 D2-D3
74-75 D4-D5
76-77 D6-D7
78-79 D8-D9
7A-7B DA-DB
AE-AF 10E-10F
7C-7D DC-DD
B0-B1 110-111
Units
V x10
mA
w
w
x 100
V x10
mA
w
w
w
x 100
V x10
mA
W
W
w
x 100
ºC x 10