07 Communication

Last modified by Devin Chen on 2024/08/19 14:28

PLC COM2 Modbus RTU

Protocol Setting (D8126)

Protocol	Description	Value of D8126
WECON PLC Protocol	Using WECON PLC Protocol	01H
MODBUS RTU Master	PLC is slave device	02H
MODBUS ASCII Master	PLC is slave device	03H
User-defined Protocol	Using User-defined Protocol	10H
MODBUS RTU Slave	PLC is master device	20H
MODBUS ASCII Slave	PLC is master device	30H

Communication format (D8120)

Item	parameter	Bit value of D8120
Item	parameter	b7	b6	b5	b4	b3	b2	b1	b0
Baud rate (Bps)	115200	1	1	0	0	-	-	-	-
	57600	1	0	1	1	-	-	-	-
	38400	1	0	1	0	-	-	-	-
	19200	1	0	0	1	-	-	-	-
	9600	1	0	0	0	-	-	-	-
	4800	0	1	1	1	-	-	-	-
Stop bit	1 bit	-	-	-	-	0	-	-	-
Stop bit	2 bit	-	-	-	-	1	-	-	-
Parity	None	-	-	-	-	-	0	0	-
	Odd	-	-	-	-	-	0	1	-
	Even	-	-	-	-	-	1	1	-
Data bit	7 bit	-	-	-	-	-	-	-	0
Data bit	8 bit	-	-	-	-	-	-	-	1
Example: the communication format is 9600.1.8.None, b7b6b5b4=1000, b3=0, b2b1=00, b 0=1. D8120=81H ( (10000001)₂=81H, 81H means hexadecimal number)

✎Note: If use Data bit=7.Parity can not choose None.

WECON PLC - MODBUS (Slave) addresses rules

PLC Bit Address
PLC Address	MODBUS Address
PLC Address	Hex	Decimal
M0 ~ M3071	0 ~ 0xBFF	0 ~ 3071
M8000 ~ M8256	0x1F40 ~ 0x2040	8000 ~ 8256
S0 ~ S999	0xE000 ~ 0xE3E7	57344 ~ 58343
T0 ~ T256	0xF000 ~ 0xF100	61440 ~ 61696
C0 ~ C255	0xF400 ~ 0xF4FF	62464 ~ 62719
X0 ~ X377	0xF800 ~ 0xF8FF	63488 ~ 63743
Y0 ~ Y377	0xFC00 ~ 0xFCFF	64512 ~ 64767
PLC Word Address
PLC Address	MODBUS Address
PLC Address	Hex	Decimal
D0 ~ D8255	0 ~ 0x203F	0 ~ 8255
T0 ~ T255	0xF000 ~ 0xF0FF	61440 ~ 61695
C0 ~ C199	0xF400 ~ 0xF4C7	62464 ~ 62663
C200 ~ C255	0xF700 ~ 0xF7FF	63232 ~ 63487

MODBUS function code introduction

Function code 0x01(01): read coil (bit address)

Frame format: Station number of slave&0x01 + start address + number of coils + CRC

No.	Data	Number of byte	Instruction
1	Station number of slave	1 byte	Value range 1~247, set by D8121
2	0x01（function code）	1 byte	Read coil
3	Start address	2 bytes
4	Number of coils	2 bytes
5	CRC	2 bytes

Function code 0x03(03): read register (word address)

Frame format: Station number of slave&0x03 + start address+ number of registers + CRC

No.	Data	Number of byte	Instruction
1	Station number of slave	1 byte	Value range 1~247, set by D8121
2	0x03 (function code)	1 byte	Read register
3	Start address	2 bytes
4	Number of registers	2 bytes
5	CRC	2 bytes

Function code 0x05(05): write single coil

Frame format: Station number of slave&0x05 + address + state of coil + CRC

No.	Data	Number of byte	Instruction
1	Station number of slave	1 byte	Value range 1~247, set by D8121
2	0x05 (function code)	1 byte	Write single coil
3	address	2 bytes
4	State of coil	2 bytes
5	CRC	2 bytes

Function code 0x06 (06): Write single register

Frame format: Station number of slave&0x06 + address + value + CRC

No.	Data	Number of byte	Instruction
1	Station number of slave	1 byte	Value range 1~247, set by D8121
2	0x06 (function code)	1 byte	Write single register
3	address	2 bytes
4	Value of register	2 bytes
5	CRC	2 bytes

Function code 0x0f(15): Write continuous coils

Frame format: Station number of slave&0x0f + start address + number of coils + length + state of coil + CRC

No.	Data	Number of byte	Instruction
1	Station number of slave	1 byte	Value range 1~247, set by D8121
2	0x0f (function code)	1 byte	Write contunuous coils
3	Start address	2 bytes
4	Number of coil	2 bytes
5	Length	1 bytes
6	State of coils	[(N+7)/8] bytes
7	CRC	2 bytes

Function code 0x10 (10): Write continuous registers

Frame format: Station number of slave&0x10 + start address + number of registers + length + value of register + CRC

No.	Data	Number of byte	Instruction
1	Station number of slave	1 byte	Value range 1~247, set by D8121
2	0x10 (function code)	1 byte	Write contunuous registers
3	Start address	2 bytes
4	Number of registers	2 bytes
5	Length	1 bytes
6	Value of register	N*2 bytes
7	CRC	2 bytes

Example

Read bit address from device

(When reading the bit address, a return value of 256 indicates that the coil is in the ON state, while a return value of 0 indicates that the coil is in the OFF state.)

Read word address from device

Write single coil

Tip: (When writing a single coil or a continuous coil, write HFF00 to turn the coil on, and write H0000 to turn off the coil.)

Write single register

Write continuous coils

Write continuous registers

PLC is slave devic

WECON PLC Protocol (COM2)

N:N network

LX3VP COM2 N:N Application

LX3VP COM2 N:N Connection

PLC built-in N:N connection protocol provides an effective way to exchange data among multiple PLC (Max. 8 devices). Technically, it only requires the twisted pair RS485 cable to connect with each PLC COM2 (in parallel).

COM2 N:N Instructions

User should put data to specified register unit. Exchanging the data among PLCs, This function only requires putting data in preset register block, all the data in this register block would share with other PLCs. There are five modes for choice, according to data volume and communication speed. See the preset register block from table below.

Station Number		Mode 0		Mode 1		Mode 2
		Bit (M)	Word(D)	Bit (M)	Word(D)	Bit (M)	Word(D)
		0	4	32	4	64	8
Master	NO. 0	--	0-3	1000-1031	0-3	1000-1063	0-7
Slave	NO. 1	--	32-35	1064-1095	32-35	1064-1127	32-39
	NO. 2	--	64-67	1128-1159	64-67	1128-1191	64-71
	NO. 3	--	96-99	1192-1223	96-99	1192-1255	96-103
	NO. 4	--	128-131	1256-1287	128-131	1256-1319	128-135
	NO. 5	--	160-163	1320-1351	160-163	1320-1383	160-167
	NO. 6	--	192-195	1384-1415	192-195	1384-1447	192-199
	NO. 7	--	224-227	1448-1479	224-227	1448-1511	224-231
Station Number		Mode 3		Mode 4
		Bit (M)	Word(D)	Bit (M)	Word(D)
		64	16	64	32
Master	NO. 0	1000-1063	0-15	1000-1063	0-31
Slave	NO. 1	1064-1127	32-47	1064-1127	32-63
	NO. 2	1128-1191	64-79	1128-1191	64-95
	NO. 3	1192-1255	96-111	1192-1255	96-127
	NO. 4	1256-1319	128-143	1256-1319	128-159
	NO. 5	1320-1383	160-175	1320-1383	160-191
	NO. 6	1384-1447	192-207	1384-1447	192-223
	NO. 7	1448-1511	224-239	1448-1511	224-255

Communication between each PLC (up to 8 PLC), please see the connection construction below (For 3 PLC interconnection).

Special devices in N: N network

Register	Description
D8120	Communication format settings
D8126	COM2 communication protocol settings, 40h means N:N Master Device, 04h means N:N Slave device
D8176	Station number, from 0 to 7, 0 means master device
D8177	Total station number, from 1 to 7, only required for master device.
D8178	Register block setting, from 0 to 5, only required for master device.
D8179	Retry count settings, only required for master device.
D8180	Timeout setting, unit: 10ms，only required for master device.
D8201	Current connection scould time
D8202	Maximum connection scould time
D8203	Master error counter
D8204~D8210	Slave error counter
D8211	Master N:N error code
D8212~D8218	Slave N:N error code
M8183	Master data transfer sequence error
M8183~M8190	Communication error flag: M8183 - No.0 (Master); M8184 - No. 1 (Slave 1) ......
M8191	Processing sending data

Communications format

Item	Parameters	b15(RS2)	b14-b8	b7	b6	b5	b4	b3	b2	b1	b0
Bit mode	8 bit	0	Retention	-	-	-	-	-	-	-	-
Bit mode	16-bit	1		-	-	-	-	-	-	-	-
Baud rate (Bps)	115200	-		1	1	0	0	-	-	-	-
	57600	-		1	0	1	1	-	-	-	-
	38400	-		1	0	1	0	-	-	-	-
	19200	-		1	0	0	1	-	-	-	-
	9600	-		1	0	0	0	-	-	-	-
	4800	-		0	1	1	1	-	-	-	-
Stop bit	1 bit	-		-	-	-	-	0	-	-	-
Stop bit	2 bit	-		-	-	-	-	1	-	-	-
Parity	None	-		-	-	-	-	-	0	0	-
	Odd	-		-	-	-	-	-	0	1	-
	Even	-		-	-	-	-	-	1	1	-
Data bit	7 bit	-		-	-	-	-	-	-	-	0
Data bit	8 bit	-		-	-	-	-	-	-	-	1

Communication error code (D8211~D8218)

Error code	Description
1	The monitoring period has elapsed, and the slave station has not responded to requests from the master station yet.
2	The other slave stations have responded to requests sent by the master station.
3	The count values in the parameter data do not match those responded by the slave stations.
4	The response messages from the slave stations are incorrect.
17	The monitoring period has elapsed,the master station has not sent a request to the next slave station yet.
20	The messages from the master station are incorrect.
33	The slave station is unresponsive.
34	The other slave stations have responded to requests sent by the master station.
35	The count values in the parameter data do not match those responded by the slave stations.
49	The slave station received requests from the master station before receiving the parameters.

Program example

LX3VP COM2 port communication parameters: 9600, 1, 8, NONE. Register block mode: 3

PLC as master

PLC as slave

✎Note:

There are two modes of N:N protocol configuration. one is LX3VP built-in N:N protocol, the other one is LX3V N:N protocol (LX3V-2RS485-BD required).
In LX3VP series PLC, only one kind of N:N configuration available. Second mode would be disabled when LX3VP built-in N:N protocol configured.

RS485-BD and ETH-BD communiaction

Please kindly check the link as below.

✎Note: at present 5V PLC can not support RS485-BD and ETH-BD

http://docs.we-con.com.cn/wiki/bdmodule/view/Main/Communication/2RS485-BD-3V/

http://docs.we-con.com.cn/wiki/bdmodule/view/Main/Communication/LX3VP-ETH-BD/