MODBUS RTU Electroplating rectifier

MAO | 2024-01-29

This Communication protocal adopts the standard Modbus protocol ，The transmission mode is RTU (hex).ModBus protocol is a master-slave protocol

The host computer(PLC, HMI,ETC) responds to the Master rectifer as the slave

Communication address ：1~32

Function code：reading and writing multiple registers 。

Data format： Via the binary cade transmission。

CRC16： Cyclic redundancy check ,from the address of the slave station on the last byte of the data area , calculates the polynonial code A001(hex)

1 Set of the communication prot

Communication way Asynchronous serial communicaton prot， RS-485。

Baud rate 19200bps

2 Byte data format HEX

. One-bit start bit

. Eight data bits

. One stop bit

. Even parity check

One-bit start bit data bits（Low-high） stop bit Check

3 Mesage frame format （Define read and write functions from the standpoint of the master station）

Send the Read rectifer register frame

Slave address	Function code	First register address	Number of refister	CRC16
1byte	1 byte	2 byte	2 byte	2 byte
1-32	03H	0000H	0003H	CrcL, CrcH

Receive the Read rectifer register frame

Slave address	Function code	Number of register	Content of rectifier register data content	CRC16
1byte	1byte	1byte	6 byte	2 byte
1-32	03H	06H	V, I, ZT	CrcL, CrcH

Write the rectifer register farme

Slave address	Function code	Frist register address	Number of register	Numbe of byte	Content of refister	CRC16
1byte	1byte	2 bytes	2 bytes	1byte	4 bytes	2bytes
1-32	10H	000AH	0002	04	F,SW	CrcL, CrcH

Receive the wirite rectifer register frame

Slave address	Function code	First register address	Number of register	CRC16
1byte	1byte	2bytes	2bytes	2bytes
1-32	10H	000AH	0002	CrcL, CrcH

List of the Function code explain：

Function	ModBus	Function code	broadcast	Number
03H	Read Holding Registers	Read the rectifier register	No	3
10H	Write Multiple Registers	Write the rectifier register	No	2

4 Rectifier register list （read register ,wirte register）：

NO	Parameter codes	Name of parameters	Address	type	Rate of Number	Remark
1	V	Display the value of voltage	0	Read rectfier register	0-9999 (10hex)
2	I	Display the value of current	1		0-9999 (10hex)
3	ZT	Dis play the state of rectifer running	2		0-3 (10hex)	0——without error 1——Overheating 2——overcurrent 3——other error
4	F	Set the value of voltate or curent to rectifier	10	Write rectfier register	0-9999 (10 hex)
5	SW	Switching valve	11	Write rectfier register	(16 hex)	Check the talbe below for expian this item

Detail of switch bit variable (SW)
Number of bit	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
State of “o” (false)					Off alarm		D13光耦截止	Stop rectifier								Model of CC
Stae of “1” (turth)					Open alarm		D13光耦导通	Start rectifier								Model of CV

Memory address table description: 1, all data types are unsigned integer (two bytes).

2. All the data with decimal points in communication transmission are replaced by integers, such as: 1.000 instead of 1000.

(i.e. ignoring the decimal point) 27.9 is replaced by 279.

3, all register data in the transmission process is expressed in hexadecimal numbers, first pass high bytes, then pass low bytes, such as transmission 279, first pass 01H, then pass 23H.

Now let me give you an example, MUDBUSPOLL for MUDBUS485(RUT) communication with our electroplate rectifier.

Connection

The tools used in this example are as follows:

1 Laptop (64-bit) with Windows 10 Home Edition operating system.

Modbuspoll (64-bit) software.(master tool)

USB to RS232 data cable.

RS232 to RS485 converter

Electroplating rectifier（slave)

I will test the electroplating rectifier in CV (Constant Voltage) operating mode, setting parameters and examining various details. I will also provide steps and illustrations.

1step:Set the parameters of the communication port.( 19200, 8, E, 1)