Wecon PLCLV5V-2RS485BD User manual

LV5V-2RS485 BD Board Manual V1.0
PLC LV5V-2RS485 BD
Board Manual
V1.0
Website: http://www.we-con.com.cn/en
Phone: [phone]

LV5V-2RS485 BD Board Manual V1.0
1 WECON technology Co., Ltd
1 Features
LX5V-2RS485-BD is used for serial communication connection and installed on the top of PLC
host.
LX5V-2RS485-BD supports Modbus RTU, Modbus ASCII, user-defined protocol and dedicated
protocol (Wecon Modbus slave station protocol, that is, PLC local protocol).
Data transfer using user-defined protocol, through RS485 converter, data communication
between various devices with RS232C unit, such as personal computers, barcode readers and
printers. In this application, data is sent and received through the data register specified by RS2
instruction.
Using dedicated protocol for data transfer, connect PLC Editor2 PC with LX5V-2RS485-BD to
complete the uploading and downloading of the program.
✎Note: This manual is only applicable when LX5V-2RS485-BD is used together with 5V series
PLC.Please refer to the LX3V-RS485-BD Manual for the use of LX5V-2RS485-BD with 3V Series PLC.
2 Appearance and terminal
LX5V-2RS485-BD
B2-
A2+
B1-
A1+
PWR
TX1 RX1 TX2
GND
RX2
Indicator light
Color
Description
PWR
White
Power light: It is always ON when the power supply connection is
normal.
TX1
Yellow
Serial port 3/serial port 5 sends.
RX1
Green
Serial port 3/serial port 5 receives.
TX2
Yellow
Serial port 4/serial port 6 sends.
RX2
Green
Serial port 4/serial port 6 receives.

LV5V-2RS485 BD Board Manual V1.0
2 WECON technology Co., Ltd
PLC with small points has a card slot, and the installation position is shown in the following figure,
where (A1+, B1-) is COM3 and (A2+, B2-) is COM4.
LX5V LX5V-2RS485-BD
B2-
A2+
B1-
A1+
PWR
TX1 RX1 TX2
GND
RX2
LX5V-2RS485-BD
B2-
A2+
B1-
A1+
PWR
TX1 RX1 TX2
GND
RX2
COM3
COM4
PLC with large points has two card slots. (A1+, B1-) of BD board on the left side is COM3, and (A2+,
B2-) is COM4. (A1+, B1-) of BD board on the right is COM5, [A2+, B2-] is COM6.
LX5V LX5V-2RS485-BD
B2-
A2+
B1-
A1+
PWR
TX1 RX1
TX2
GND
RX2
LX5V-2RS485-BD
B2-
A2+
B1-
A1+
PWR
TX1 RX1 TX2
GND
RX2
COM3
COM4
LX5V LX5V-2RS485-BD
B2-
A2+
B1-
A1+
PWR TX1 RX1 TX2
GND
RX2
LX5V-2RS485-BD
B2-
A2+
B1-
A1+
PWR
TX1 RX1 TX2
GND
RX2
COM5
COM6

LV5V-2RS485 BD Board Manual V1.0
3 WECON technology Co., Ltd
LX5V LX5V-2RS485-BD
B2-
A2+
B1-
A1+
PWR
TX1 RX1 TX2
GND
RX2
LX5V-2RS485-BD
B2-
A2+
B1-
A1+
PWR
TX1 RX1 TX2
GND
RX2
LX5V-2RS485-BD
B2-
A2+
B1-
A1+
PWR
TX1 RX1 TX2
GND
RX2
COM5
COM6
LX5V-2RS485-BD
B2-
A2+
B1-
A1+
PWR
TX1 RX1 TX2
GND
RX2
COM3
COM4
3 Serial communication function
Serial port
Communication protocol
Communication
instruction
Communication
interface
COM3
Modbus RTU protocol;
Modbus ASCII protocol;
User-defined protocol
Dedicated protocol (supports program upload
and download and HMI monitoring).
RS2 instruction
RS485
COM4
COM5
COM6
4 Parameter configuration
1Open the host computer and create a new project, double-click “Project Manager” →
“Extended Function” → "BD Board Configuration" Note to enter “BD settings” interface;
2Select "LX5V-2RS485" in the device bar on the right side of the BD board configuration
interface and double-click to add it to the corresponding slot position of PLC (slot 1 or 2, the
software will select slot 1 by default. You could right-click it to move to slot 2);
3After adding BD board to the machine slot, double-click or right-click to select configuration
parameters to enter LX5V-2RS485-BD configuration parameters interface, as shown in the following
figure. Parameters such as baud rate, data bit, stop bit, check bit and station number are configured
in this interface.

LV5V-2RS485 BD Board Manual V1.0
4 WECON technology Co., Ltd
✎Note: This function is only supported in the following host computer and slave computer
versions:
Supported host computer versions: Wecon PLC Editor 2 2.1.204 and above, as shown in the
following figure:

LV5V-2RS485 BD Board Manual V1.0
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Supported slave computer versions: 2.061 and above, as shown in the following figure:
The parameter configuration interface is as follows:
Functional description of each configuration item:
(1) Whether to set: Indicates whether the configuration is effective. True is effective, and False is
not.
(2) Communication settings:
Baud rate: Indicates the baud rate of serial communication and the number of bits
transmitted per second. The maximum baud rate supported is 115200bps.
Data bit: Indicates the number of data bits of serial communication, and the value range is

LV5V-2RS485 BD Board Manual V1.0
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7 to 8 digits.
Stop bit: Indicates the number of stop bits in serial communication, and the value range is
1 to 2 digits.
Parity bit: Indicates whether to add check bits during serial communication, and check
types. Odd check and even check are commonly used.
Timeout (10ms): Configuration for the master station, indicating the maximum waiting
time between the request and the reply. The unit is 10ms, and the configuration here is 10,
which means 10*10ms=100ms.
Sending interval (0.1 ms): Configuration for the master station, indicating the time when
the communication is completed and the next request is sent.
Agreement: Currently supported protocols are: user-defined protocol, dedicated protocol,
Modbus RTU, Modbus ASCII.
User-defined protocol: Users need to organize request frames by themselves, and
process response frames after receiving response data.
Dedicated protocol: WECON Modbus protocol (PLC local protocol) is used for program
upload and download, HMI monitoring protocol.
(3) Agreement related:
Station NO. (0 is the main station): The value range is 0 to 255. Non-0 indicates the slave
station number, and 0 indicates the master station.
Whether to enable the starter: Effective under user-defined protocol. When enabled, a
user-defined starter of one-byte is sent first before sending user data.
Whether to enable the terminator: Effective under user-defined protocol. When enabled,
a user-defined terminator of one-byte is sent again after the user data is sent.
(4) Terminator: Effective under user-defined protocol.
(5) Inter-character timeout (0.1 ms): Mainly used to judge whether a complete response frame is
received. After receiving a byte, if there is no new byte is received beyond the time-out interval
between characters, it indicates that the data of the previous frame has been received.
(6) Bit mode: It is divided into 8-bit and 16-bit modes, which are mainly used to define the storage
mode of data received by user-defined protocol. Assume that the user-defined protocol
receives two bytes of data, 0x12 and 0x13, and stores them in the device starting with D100.
The storage mode of 16-bit mode is as follows:
(High 8 bits)
(Low 8 bits)
D100
0x13
0x12
D101
No data
No data
The storage mode of 8-bit mode is as follows:
(High 8 bits)
(Low 8 bits)
D100
0x00
0x12
D101
0x00
0x13
5 RS2 instruction
In the case of user-defined protocol: The instruction is a communication receiving and sending
instruction. The starting data of the specified (S) is taken out (M) and sent, and the data received by
the serial port is stored in (D), and store (N), sent by the communication port specified by (N1).
In the case of Modbus master protocol: The instruction is a setting interface for sending protocol
frames by the master station. According to the station number function code (S), slave station
address (M), and length (D) set by the instruction, and the function code to determine whether N
data is needed to automatically combine to send and receive protocol frames. If it is a read type

LV5V-2RS485 BD Board Manual V1.0
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function code, the data will be written to (N) and sent by the communication port specified by (N1).
-[RS2 (S) (M) (D) (N) (N1)]
Content, range and data type
In the case of user-defined protocol
Parameter
Content
Range
Data type
Data type
(label)
(S)
The starting address of the register area where
the data to be sent is stored
-
Unsigned
BIN16 bits
ANY16
(M)
The length (in bytes) of the data to be sent
0 to 528
Unsigned
BIN16 bits
ANY16
(D)
The start number of device that stores written
data
-
Unsigned
BIN16 bits
ANY16
(N)
Number of data written in bytes
0 to 528
Unsigned
BIN16 bits
ANY16
(N1)
Specify communication port
-
Unsigned
BIN16 bits
ANY16
Modbus protocol
Parameter
Content
Range
Data type
Data type
(label)
(S)
The high byte stores the station number of the
slave station, and the low byte stores Modbus
function codes.
-
Unsigned
BIN16 bits
ANY16
(M)
The slave address provided by the slave, reads or
writes data from this address of the slave.
-
Unsigned
BIN16 bits
ANY16
(D)
Length. The length read or written by Modbus,
and the unit is determined by the function code.
-
Unsigned
BIN16 bits
ANY16
(N)
Start address for reading or writing data
-
Unsigned
BIN16 bits
ANY16
(N1)
Specify communication port
-
Unsigned
BIN16 bits
ANY16
Device used
Instruction
Parameter
Devices
Offset
modification
Pulse
extension
X
Y
M
S
SM
T (bit)
C (bit)
LC
(bit)
HSC
(bit)
D.b
KnX
KnY
KnM
KnS
T
C
D
R
SD
LC
HSC
K
H
E
[D]
XXP
RS2
(S)
●
●
●
●
●
●
(M)
●
●
●
●
●
●
(D)
●
●
●
●
●
●
(N)
●
●
●
●
●
●
(N1)
●
●
Function
The parameter (N1) is the specified serial port, K2 for COM3 (BD1), K3 for COM4 (BD1), K4 for
COM5 (BD2), and K5 for COM6 (BD2).

LV5V-2RS485 BD Board Manual V1.0
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5.1 User-defined protocol
When the communication protocol is set to user-defined protocol, in the case of the contact before
the RS2 instruction is set on, the “sending control on" is also set ON, and the sending length (M) is
not 0, the data of (S) will be sent out by (M) bytes, and then enter the wait receiving mode. When
the data is received, (N) bytes of data will be stored in (D). After receiving (N) pieces of data, the
"Accept control/Receive prompt" will be set on.
In addition, when the sending length (M) is 0, it will be in the receive-only mode. When the
receiving length (N) is 0, it will be in the send-only mode.
Example:
When M1 is ON, the sending and receiving data of communication after instruction execution are
stored as follows:
5.2 Modbus protocol
When the protocol is set to Modbus master station protocol (whether RTU or ASCII), and the
contact point before the RS2 instruction is set ON, the RS2 instruction will judge whether the data of
(N) is needed to send the combined data frame according to station number function code (S), slave
station address (M), the length (D) and function code.
Example:
(S)
The high byte stores the station number of the slave station, and the low byte stores
the Modbus function code.
(M)
Slave station address The address provided by the slave station will read or write data
from the address of slave station.
(D)
Length. The length read or written by Modbus, and the unit is determined by the
function code.
(N)
The starting address for reading or writing data.
(N1)
Specify communication port.

LV5V-2RS485 BD Board Manual V1.0
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✎Note:
1The RS2 instruction allows parameters to be represented by K and H constants, but with
different restrictions on different protocols.
2When the protocol is user-defined protocol, S and D cannot be constants, otherwise an error
(3X89H) will be reported.
3When the protocol is Modbus protocol, N cannot be a constant, otherwise an error (3X89H)
will be reported.
4When the protocol is RTU protocol, only 8 bits of data can be selected.
5If the serial port parameters are set differently, it may be in normal communication. However,
it is recommended that to set consistent serial port parameters to avoid other failures.
6At present, RS2 instructions cannot be used in interrupts and events.
Error code
Error code
Content
4085H
(S), (M), (D) and (N) read address out of range of the device.
4084H
Parameter value is out of the specified range.
COM3
3280H
COM3 data reception error. There may be interference on the communication cable,
it is recommended to connect GND.
3281H
COM3 data reception timed out. Check the wiring, whether the serial port parameter
settings correspond to master and slave, and whether there is interference. Check
whether the response from the station is too late. It is recommended to increase the
“sending interval".
3282H
COM3 CRC validation error. There may be interference on the communication cable,
it is recommended to connect GND.
3283H
COM3 LRC validation error. There may be interference on the communication cable, it
is recommended to connect GND.
3284H
COM3 station number is incorrectly configured. Check the slave station number
setting, and check whether there is any problem with the receiving and sending
mechanism from slave.
3285H
COM3 send buffer overflow. If this error appears, please contact your technician.
3286H
COM3 function code error. Check whether the set function code is supported by PLC.
3287H
COM3 address error. Check whether the slave station has this address. (Please refer
to Modbus exception 02).
3288H
COM3 length error. Check whether the communication length exceeds the length
range specified by Modbus protocol or user-defined protocol.
3289H
COM3 data error. Check the parameters of the instruction for errors. Check whether
the set value is supported by the slave station. (Please refer to Modbus exception 03).
328AH
COM3 slave station is busy. Message returned from slave station: Slave station is
busy. (Please refer to Modbus exception 06).
328BH
COM3 slave does not support function codes. Check whether this function code is
supported by the slave station. (Please refer to Modbus exception 01).
328CH
COM3 slave failure. Message returned from slave station: Slave station failed, please
check whether slave station failed (Please refer to Modbus exception 04).
328DH
COM3 slave confirmation. Message returned from slave station: slave station
confirmation. (Please refer to Modbus exception 05).
328EH
COM 3 does not currently support this instruction or function. When set to slave
protocol, the communication instructions related to master station or master station
functions cannot be used. Please change the protocol or close the contact before the

LV5V-2RS485 BD Board Manual V1.0
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corresponding instruction or close the corresponding communication function.
328FH
COM3 sending timed out. If this error appears, please contact your technician.
32A0H
COM3 unavailable gateway Message returned from the station: unavailable gateway.
(Please refer to Modbus exception 0A).
32A1H
COM3 indicates that no response was obtained from the target device. Message
returned from the station: The device is not in the network. (Please refer to Modbus
Exception 0B).
COM4
3380H
COM4 data reception error. There may be interference on the communication cable,
it is recommended to connect GND.
3381H
COM4 data reception timed out. Check the wiring, whether the serial port parameter
settings correspond to master and slave, and whether there is interference. Check
whether the response from the station is too late. It is recommended to increase the
“sending interval".
3382H
COM4 CRC validation error. There may be interference on the communication cable,
it is recommended to connect GND.
3383H
COM4 LRC validation error. There may be interference on the communication cable, it
is recommended to connect GND.
3384H
COM4 station number is incorrectly configured. Check the slave station number
setting, and check whether there is any problem with the receiving and sending
mechanism from slave.
3385H
COM4 send buffer overflow. If this error appears, please contact your technician.
3386H
COM4 function code error. Check whether the set function code is supported by PLC.
3387H
COM4 address error. Check whether the slave station has this address. (Please refer
to Modbus exception 02).
3388H
COM4 length error. Check whether the communication length exceeds the length
range specified by Modbus protocol or user-defined protocol.
3389H
COM4 data error. Check the parameters of the instruction for errors. Check whether
the set value is supported by the slave station. (Please refer to Modbus exception 03).
338AH
COM4 slave station is busy. Message returned from slave station: Slave station is
busy. (Please refer to Modbus exception 06).
338BH
COM4 slave does not support function codes. Check whether this function code is
supported by the slave station. (Please refer to Modbus exception 01).
338CH
COM4 slave failure. Message returned from slave station: Slave station failed, please
check whether slave station failed. (Please refer to Modbus exception 04).
338DH
COM4 slave confirmation Message returned from slave station: slave station
confirmation. (Please refer to Modbus exception 05).
338EH
COM4 does not currently support this instruction or function. When set to slave
protocol, the communication instructions related to master station or master station
functions cannot be used. Please change the protocol or close the contact before the
corresponding instruction or close the corresponding communication function.
338FH
COM4 send timed out. If this error appears, please contact your technician.
33A0H
COM4 unavailable gateway Message returned from the station: unavailable gateway.
(Please refer to Modbus exception 0A).
33A1H
COM4 indicates that no response was obtained from the target device. Message
returned from the station: The device is not in the network. (Please refer to Modbus
Exception 0B).

LV5V-2RS485 BD Board Manual V1.0
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COM5
3480H
COM5 data reception error. There may be interference on the communication cable,
it is recommended to connect GND.
3481H
COM5 data reception timed out. Check the wiring, whether the serial port parameter
settings correspond to master and slave, and whether there is interference. Check
whether the response from the station is too late. It is recommended to increase the
“sending interval".
3482H
COM5 CRC validation error. There may be interference on the communication cable,
it is recommended to connect GND.
3483H
COM5 LRC validation error. There may be interference on the communication cable, it
is recommended to connect GND.
3484H
COM5 station number is incorrectly configured. Check the slave station number
setting, and check whether there is any problem with the receiving and sending
mechanism from slave.
3485H
COM5 send buffer overflow. If this error appears, please contact your technician.
3486H
COM5 function code error. Check whether the set function code is supported by PLC.
3487H
COM5 address error. Check whether the slave station has this address. (Please refer
to Modbus exception 02).
3488H
COM5 length error. Check whether the communication length exceeds the length
range specified by Modbus protocol or user-defined protocol.
3489H
COM5 data error. Check the parameters of the instruction for errors. Check whether
the set value is supported by the slave station. (Please refer to Modbus exception 03).
348AH
COM5 slave station is busy. Message returned from slave station: Slave station is
busy. (Please refer to Modbus exception 06).
348BH
COM5 slave does not support function codes. Check whether this function code is
supported by the slave station. (Please refer to Modbus exception 01).
348CH
COM5 slave failure. Message returned from slave station: Slave station failed, please
check whether slave station failed. (Please refer to Modbus exception 04).
348DH
COM5 slave station confirmation Message returned from slave station: slave station
confirmation. (Please refer to Modbus exception 05).
348EH
COM5 does not currently support this instruction or function. When set to slave
protocol, the communication instructions related to master station or master station
functions cannot be used. Please change the protocol or close the contact before the
corresponding instruction or close the corresponding communication function.
348FH
COM5 send timed out. If this error appears, please contact your technician.
34A0H
COM5 unavailable gateway Message returned from the station: unavailable gateway.
(Please refer to Modbus exception 0A).
34A1H
COM5 indicates that no response was obtained from the target device. Message
returned from the station: The device is not in the network. (Please refer to Modbus
Exception 0B).
COM6
3580H
COM6 data reception error. There may be interference on the communication cable,
it is recommended to connect GND.
3581H
COM6 data reception timed out. Check the wiring, whether the serial port parameter
settings correspond to master and slave, and whether there is interference. Check
whether the response from the station is too late. It is recommended to increase the
“sending interval".
3582H
COM6 CRC validation error. There may be interference on the communication cable,

LV5V-2RS485 BD Board Manual V1.0
12 WECON technology Co., Ltd
it is recommended to connect GND.
3583H
COM6 LRC validation error. There may be interference on the communication cable, it
is recommended to connect GND.
3584H
COM6 station number is incorrectly configured. Check the slave station number
setting, and check whether there is any problem with the receiving and sending
mechanism from slave.
3585H
COM6 send buffer overflow. If this error appears, please contact your technician.
3586H
COM6 function code error. Check whether the set function code is supported by PLC.
3587H
COM6 address error. Check whether the slave station has this address. (Please refer
to Modbus exception 02).
3588H
COM6 length error. Check whether the communication length exceeds the length
range specified by Modbus protocol or user-defined protocol.
3589H
COM6 data error. Check the parameters of the instruction for errors. Check whether
the set value is supported by the slave station. (Please refer to Modbus exception 03).
358AH
COM6 slave station is busy. Message returned from slave station: Slave station is
busy. (Please refer to Modbus exception 06).
358BH
COM6 slave does not support function codes. Check whether this function code is
supported by the slave station. (Please refer to Modbus exception 01).
358CH
COM6 slave failure. Message returned from slave station: Slave station failed, please
check whether slave station failed. (Please refer to Modbus exception 04).
358DH
COM6 slave station acknowledges. Message returned from slave station: slave station
confirmation. (Please refer to Modbus exception 05).
358EH
COM6 does not currently support this instruction or function. When set to slave
protocol, the communication instructions related to master station or master station
functions cannot be used. Please change the protocol or close the contact before the
corresponding instruction or close the corresponding communication function.
358FH
COM6 send timed out. If this error appears, please contact your technician.
35A0H
COM6 unavailable gateway Message returned from the station: unavailable gateway.
(Please refer to Modbus exception 0A).
35A1H
COM6 indicates that no response was obtained from the target device. Message
returned from the station: The device is not in the network. (Please refer to Modbus
Exception 0B).
6 Address mapping
When the BD board configures the serial port protocol as Modbus slave station protocol, the
address mapping relationship accessed by the master station is as follows:
Word address
Address type
Occupation
Address range
Decimal
address
Total reserved
address size
T0 to T511
512 WORD
0x0000 to 0x01ff
0
1536
C0 to C255
256 WORD
0x0600 to 0x06ff
1536
1024
LC0 to LC255
512 WORD
0x0A000 to 0x0BFF
2560
1024
HSC0 to HSC15
128 WORD
0x0E00 to 0x0E1F
3584
512
D0 to D7999
8000 WORD
0x1000 to 0x2F3F
4096
16384
SD0 to SD4095
4096 WORD
0x5000 to 0x5FFF
20480
12288
R0 to R30000
30000 WORD
0x8000 to 0xF52F
32768
30000

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Bit address
Address type
Occupation
Address range
Decimal
address
Total reserved
address size
T0 to T511
512 bits
0x0000 to 0x01ff
0
1536
C0 to C255
256 bits
0x0600 to 0x06ff
1536
1024
LC0 to LC255
256 bits
0x0A00 to 0x0AFF
2560
1024
HSC0 to HSC15
64 bits
0x0E00 to 0x0E0F
3584
512
M0 to M8000
8192 bits
0x1000 to 0x2F3F
4096
16384
SM0 to SM4095
4096 bits
0x5000 to 0x5FFF
20480
12288
Reserved
0x8000 to 0xBFFF
16383
S0 to S4095
4096 bits
0xC000 to 0xCFFF
49152
8192
X0 to X1023
1024 bits
0xE000 to 0xE3FF
57344
4096
Y0 to Y1023
1024 bits
0xF000 to 0xF3FF
61440
4096
When using the Modbus master station to access the slave station, the RS2 instruction specifies the
following address:
Example 1: Read 10 registers starting from slave station (station NO.1) D0 and store them in 10
devices starting from local D0:
The function code of this instruction is 3, which indicates reading register, and the address H1000 in
it is the starting address of "D0 to D7999" by inquiring the "word address table", which corresponds
to the address of D0.
Example 2: Read 10 bit devices starting from slave station (station NO.1) M0 and store them in local
D0 device (because D0 can store the value of 16 bit devices, zero padding will be performed):
The function code of the instruction is 1, which indicates read coil, and the address H1000 in it is
the starting address of “M0 to M8000" by inquiring the "bit address table", which corresponds to
the address of M0. If slave stations M0 and M1 are 1, and the rest are 0, the value in D0 is H0300
(not H0003).
7 Special devices for BD board
BD1:
SD label
Content
SD label
Content
SM2000
COM3 sending control on
SD2000
Display 0x1062 after 485BD is
recognized after power-on.
SM2001
COM3 send control/send prompt
SD2001
Display 485BD version information after
485BD is recognized after power-on.
SM 2002
COM3 reception control on
SD 2002
BD1 last error
SM 2003
COM3 accept control/receive
prompt
SD 2003
BD1 current error
SM2004
COM3 communication complete flag
SD2004
BD1 error times
SM 2005
COM4 sending control on
SD 2005
BD1 error communication port.

LV5V-2RS485 BD Board Manual V1.0
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SM 2006
COM4 send control/send prompt
SD2006
BD1 communication timeout (1ms).
SM 2007
COM4 reception control on
SM2008
COM4 accept control/receive
prompt
SM2009
COM4 communication complete flag
BD2:
SD label
Content
SD label
Content
SM2020
COM5 sending control on
SD2020
Display 0x1062 after 485BD is
recognized after power-on.
SM2021
COM5 send control/send prompt
SD2021
Display 485BD version information after
485BD is recognized after power-on.
SM 2022
COM5 reception control on
SD2022
BD2 last error
SM2023
COM5 accept control/receive
prompt
SD2023
BD2 current error
SM2024
COM5 communication complete flag
SD2024
BD2 error times
SM2025
COM6 sending control on
SD2025
BD2 error communication port.
SM2026
COM6 send control/send prompt
SD2026
BD2 communication timeout (1ms).
SM2027
COM6 reception control on
SM2028
COM6 accept control/receive
prompt
SM2029
COM6 communication complete flag
8 Examples
8.1 Modbus RTU slave station
Configure COM3 port as Modbus RTU slave. COM3 parameters are configured as follows:

LV5V-2RS485 BD Board Manual V1.0
15 WECON technology Co., Ltd
Configure the station number to 1 and click OK, and the download program will take effect. (Ensure
that the baud rate, data bit, stop bit and parity bit configuration are consistent with the master
station)
8.2 Modbus RTU master station
Configure COM4 port as the Modbus RTU master station, and read the 125 word devices starting
from the station address once every 100ms.
COM4 parameters are configured as follows:
The station number is configured as 0 to indicate the master station protocol.
The ladder diagram is configured as follows:
8.3 Dedicated protocol
Configure COM3 port as a dedicated protocol, and use this serial port to upload and download
programs.
COM3 parameters are configured as follows:

LV5V-2RS485 BD Board Manual V1.0
16 WECON technology Co., Ltd
PLC Editor2 uses this serial port communication: PC uses USB to RS485 converter to connect with
BD board at this time.

LV5V-2RS485 BD Board Manual V1.0
17 WECON technology Co., Ltd
8.4 User-defined protocol
Configure COM3 port as user-defined protocol, and simulate Modbus RTU instruction. A read
instruction is sent to the slave station every 100ms, to read 125 word devices starting from slave
station address 0, and store the response data in D100 device, and judge whether the value of the
word device at address 0 is 100. If yes, set M10 and reset M20; If not, set M20 and reset M10.
COM3 parameters are configured as follows:

LV5V-2RS485 BD Board Manual V1.0
18 WECON technology Co., Ltd
The ladder diagram is configured as follows: