Circutor CVM-MINI SERIES, Instruction Manual

Page: 23 / 26

Page 23 of 26
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 8 bit binary, hexadecimal 0-9, A-F.
2 hexadecimal characters contained in each 8-bit field in
the message.
Bits per byte 8 data bits.
Field Check-Error CRC Type (Cyclical Redundancy Check).
Modbus functions used:
Function 01 Reading the status of the relays.
Function 03 and 04 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)
Function 05 Writing a relay.
6.1 MODBUS memory map
PARAMETER SYMBOL
Instant Maximum Minimum Units
Voltage phase V L1 00-01 60-61 C0-C1 V x10
Current A L1 02-03 62-63 C2-C3 mA
Active power kW L1 04-05 64-65 C4-C5 w
Reactive power Kvar L1 06-07 66-67 C6-C7 w
Apparent power kV·A L1 4A-4B AA-AB 10A-10B
Power factor PF L1 08-09 68-69 C8-C9 x 100
Voltage phase V L2 0A-0B 6A-6B CA-CB V x10
Current A L2 0C-0D 6C-6D CC-CD mA
Active power kW L2 0E-0F 6E-6F CE-CF w
Reactive power Kvar L2 10-11 70-71 D0-D1 w
Apparent power kV·A L2 4C-4D AC-AD 10C-10D w
Power factor PF L2 12-13 72-73 D2-D3 x 100
Voltage phase V L3 14-15 74-75 D4-D5 V x10
Current A L3 16-17 76-77 D6-D7 mA
Active power kW L3 18-19 78-79 D8-D9 W
Reactive power
Kvar L3
1A-1B 7A-7B DA-DB
W
Apparent power kV·A L3 4E-4F AE-AF 10E-10F w
Power factor PF L3 1C-1D 7C-7D DC-DD x 100
Temperature ºC 50-51 B0-B1 110-111 ºC x 10