Algodue ELETTRONICA UPM307 - Additional Voltage and Current Input Wiring; 3-Phase, 3-Wire, 1 CT Wiring; 3-Phase, 2-Wire, 1 CT Wiring; Single-Phase Wiring Diagram

4-1
ENGLISH
Read registers
MODBUS protocol manual
4. READ REGISTERS
(Function code $03)
The master communication device can send commands to the instrument to read its measured
values, status and setup. More registers can be read, at the same time, sending a single command,
only if the registers are consecutive.
According to the used MODBUS protocol mode, the read command is structured as follows.
MODBUS ASCII/RTU
Values contained both in Query or Response messages are in hexa format.
Query example in case of MODBUS ASCII/RTU: 0103000000044409
Example Byte Description No. of bytes
01 - Slave address 1
03 - Function code 1
00 High
Starting register 2
00 Low
00 High
No. of words to be read 2
04 Low
44 High
Error check (CRC) 2
09 Low
Response example in case of MODBUS ASCII/RTU: 0103080000000000000FCFD073
Example Byte Description No. of bytes
01 - Slave address 1
03 - Function code 1
08 - Byte count 1
00 High
Requested data 8
00 Low
00 High
00 Low
00 High
00 Low
0F High
CF Low
D0 High
Error check (CRC) 2
73 Low