Circutor CEM-C12c, Instruction Manual

Page: 18 / 28

7.- RS-485 COMMUNICATIONS
The
CEM-C12c
has one RS-485 communications port to view the measurement data and configure
the devices. The visualization and configuration can also be done through the CIRCUTOR PowerStudio
software.
Note:
Default values of RS-485 communication:
No. of peripheral 1, 9600 bps, No parity, 8 data bits
and 1 stop bit.
7�1�- MODBUS PROTOCOL
In the Modbus protocol, the
CEM-C12c
device uses the RTU (Remote Terminal Unit) mode.
The Modbus functions implemented in the device are as follows:
Function 0x03 : Reading integer registers
Function 0x10 : Writing multiple registers
7�1�1� READING EXAMPLE: Function 0x03�
Question: Voltage value
Address Function
Initial
register
No� of
registers
CRC
01 03 0000 0002 C40B
Address: 01
, Peripheral number: 1 in decimals.
Function: 03 , Read function.
Initial Register: 0000
, register on which the reading will start. (Modbus address).
No of registers: 0002 , number of registers read.
CRC: C40B , CRC Character.
Response:
Address Function No of Bytes
Register
no 1
Register
no 2
CRC
01 03 02 0000 091F 359A
Address: 01 , Responding peripheral number: 1 in decimals.
Function: 03 , Read function.
No� of bytes: 02
, No. of bytes received.
Register: 091F , value of the voltage :0000091F : 2335 → 233.5V
CRC: 359A
, CRC Character.
7�1�2� WRITING EXAMPLE: Function 0x10�
Question: Modify the Modbus baud rate to 9600 bps
Address Function
Initial
Register
No of
Registers
No of Bytes Value CRC
01 10 0064 0001 02 0001 xxxx
18
CEM-C12c
Instruction Manual