8.2.- MODBUS PROTOCOL
In the Modbus protocol, the CVM-C11 device uses the RTU (Remote Terminal Unit) mode.
The Modbus functions implemented in the device are as follows:
Function 0x01: Reading a relay.
Function 0x02: Reading a digital input.
Function 0x03 and 0x04: Reading integer logs.
Function 0x05: Writing a relay.
Function 0x10: Writing multiple logs.
8.2.1.- READING EXAMPLE: FUNCTION 0x04.
Question: Instantaneous value of the phase voltage of L1
Address Function
Initial
Register
No. of
Registers
CRC
0A 04 0000 0002 70B0
Address: 0A, Peripheral number: 10 in decimals.
Function: 04, Read function.
Initial Register: 0000, on which the reading will start.
No. of Registers: 0002, number of registers read.
CRC: 70B0, CRC Character.
Response:
Address Function No. of Bytes Register No. 1
Register
No. 2
CRC
0A 04 04 0000 084D 8621
Address: 0A, Responding peripheral number: 10 in decimals.
Function: 04, Read function.
No. of bytes: 04, No. of bytes received.
Registers: 0000084D, value of the phase voltage of L1: VL1 x 10 : 212.5V
CRC: 8621, CRC Character.
Note: Every Modbus frame has a maximum limit of 20 variables (40 logs).
8.2.2.- WRITING EXAMPLE: FUNCTION 0x05.
Question: Deleting maximum and minimum values.
Address Function
Initial
Register
Value CRC
0A 05 0834 FF00 CEEF
Address: 0A, Peripheral number: 10 in decimal.
Function: 05, Read function.
Initial Register: 0834, Register of the parameter for deleting maximum and minimum values.
Value: FF00, we indicate that we want to delete the maximum and minimum values.
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CVM-C11
Instruction Manual
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