13 Ethernet Communication

Last modified by Wecon on 2025/09/03 21:03

Overview of Ethernet

IP Address Concept

IP addresses consist of network addresses and host addresses, which are distinguished by subnet masks. If a programming device (such as a PC) needs to be connected to a factory LAN via a network card, the programming device and the PLC must be in the same subnet. The IP address is combined with a subnet mask to specify the subnet of the device.

No.	Network equipment 1			Network equipment 2			Network connection
	IP	Subnet mask	Network address	IP	Subnet mask	Network address
1	192.168.0.1	255.255.255.0	192.168.0.0	192.168.0.10	255.255.255.0	192.168.0.0	Yes
2	192.168.0.1	255.255.255.0	192.168.0.0	192.168.1.10	255.255.255.0	192.168.1.0	No
3	192.168.0.1	255.255.255.1	192.168.0.1	192.168.0.10	255.255.255.1	192.168.0.0	No

When logical operation of IP address and subnet mask is performed, the network address can be calculated. If the addresses are in the same network, it means that communication can be carried out. For instance:

Setting PC Network Address

1.Open the control panel->Network and Internet->Network and sharing center;

2.Click on the local link->Attributes->Internet Protocol Version 4;

3.Set the IP address and subnet mask that are within the same network address as PLC. Note that IP addresses that have been used in LAN cannot be set. If the IP of PLC is 192.168. 8.8 and the subnet mask is 255.255. 255.0, the IP address as shown in the following figure can be set to connect the PC to PLC.

Testing Network Connection Status

Test the connection status of PC and PLC via ping command.

1.win+R key, input cmd;

2.If PLC’s IP address is 192.168.8.8;

(1)Enter ping 192.168. 8.8 command and press Enter. If 100% missing is displayed, it means that it cannot be connected with PLC.

(2)Enter ping 192.168. 8.8 command and press Enter. If 0% missing is displayed, it means that it can be connected with PLC.

(3)“ping network equipment ip”command can only be used for four times . If it needs to further perform ping , please use the command “ping network equipmentip -t”, as shown in following figure:

Ethernet connection between PLC Editor2 and PLC

1. Transmission settings->Ethernet configuration->Input the IP address of PLC; (note: the address of the network card should be in the same network segment with PLC)

2.Click the communication test to confirm the communication;

3.After successful connection, click “select” to operate PLC.

Ethernet Search Function of PLC Editor 2

1. Transmission settings->Network card selection->Equipment search (note: the address of the network card should be in the same network segment with PLC), select “connect PLC” at 1 or the network card that is within the same network segment with PLC, and click 2 to search PLC equipment in LAN.

2.Search interface is shown as follows. Click search to display the PLC equipment in the LAN, select the corresponding equipment and click OK to communicate.

3.IP address at 1 is automatically filled in. Click the communication test to test whether the communication is normal. if it is normal, click “select” button to complete the connection configuration.

Ethernet Configuration

IP Address Setting

(1) Setting via programming software

Project management->parameters->PLC parameter->Ethernet configuration.

After modification, check the parameter items through PLC download; after download, click STOP->RUN to complete.

Note: Modbus TCP Server supports maximum connections, which is used to set the maximum number of external Modbus TCP clients that can be connected to PLC simultaneously, with the range being 2~8.

(2) Setting via special device

Write IP address, subnet mask and default gateway in SD2680~SD2691;

When SM2680 is set as ON, open static IP function;

When SM2683 is set as ON, the sign IP can be modified;

STOP->RUN or the new IP address takes effect after power-on again.

SM sign	Name	Content	R/W	SD label	Name
SM2680	Statically set IP switch	ON: static setting OFF: The IP address is automatically configured by router DHCP, and the IP cannot be modified STOP->RUN	R/W	SD2680	The first byte of the IP address
SM2681	Display current network information	Refresh the current IP gateway subnet mask after being set as ON. OFF after refresh is completed.	R/W	SD2681	The second byte of the ip address
SM2682	Display current MAC information (reserved)	Refresh the current MAC after being set as ON. OFF after refresh is completed.	R/W	SM2682	The third byte of the ip address
SM2683	IP, subnet mask, gateway modification sign	ON: can be modified OFF: cannot be modified (When being set as ON, STOP->RUN; it can be automatically changed to OFF after modification)	R/W	SD2683	The fourth byte of the ip address
SM2684				SD2684	The first byte of subnet mask
SM2685				SD2685	The second byte of subnet mask
SM2686				SD2686	The third byte of subnet mask
SM2687				SD2687	The fourth byte of subnet mask
SM2688				SD2688	Default gateway first byte
SM2689				SD2689	Default gateway second byte
SM2690				SD2690	Default gateway third byte
SM2691				SD2691	Default gateway fourth byte

TCP Protocol Concept

TCP protocol is a Transport Control Protocol, which is a connection-oriented and reliable transport layer protocol. Connection-oriented means that a normal TCP transmission needs to be completed by establishing a specific virtual circuit connection between TCP client and TCP server. To transmit data over TCP, a connection must be established between hosts at both ends.

List of Ethernet-related Special Devices

SM sign	Name	Content	R/W	Power-down save
SM2681	Display current network information	Refresh the current IP, subnet mask and default gateway after being set as ON; and then being set as OFF upon completion of refresh	R/W	×
SM2682	Display current MAC information	Refresh the current MAC after being set as ON. OFF after refresh is completed.	R/W	×
SM2683	IP, subnet mask, gateway modification sign	ON: can be modified OFF: cannot be modified (When being set as ON, STOP->RUN; it can be automatically changed to OFF after modification)	R/W	√
SM2684	Network card connection status	ON: network connected OFF: network not connected; check if the network cable is connected	R	√
SM2692	MAC address modification sign	ON: can be modified OFF: cannot be modified (When being set as ON, STOP->RUN; it can be automatically changed to OFF after modification)	R/W	√
SM2700	Modbus TCP keep-alive mechanism	ON: Open OFF: Close (default)	R/W	√
SM2701	Forced shutdown of Modbus TCP server	ON: Open OFF: Close (default) (after being enabled, it will be automatically changed into OFF after shutdown)	R/W	×
SM2710	Ethernet error sign	ON: there is an Ethernet error, please check SD2710 and SD2711 OFF: there is no Ethernet error	R	×
SM2740	ModbusTCP server connection status 1	ON: Client side has been connected OFF: Client side hasn’t been connected	R	×
SM2760	ModbusTCP server connection status 2	ON: Client side has been connected OFF: Client side hasn’t been connected	R	×
SM2780	ModbusTCP server connection status 3	ON: Client side has been connected OFF: Client side hasn’t been connected	R	×
SM2800	ModbusTCP server connection status 4	ON: Client side has been connected OFF: Client side hasn’t been connected	R	×
SM2820	ModbusTCP server connection status 5	ON: Client side has been connected OFF: Client side hasn’t been connected	R	×
SM2840	ModbusTCP server connection status 6	ON: Client side has been connected OFF: Client side hasn’t been connected	R	×
SM2860	ModbusTCP server connection status 7	ON: Client side has been connected OFF: Client side hasn’t been connected	R	×
SM2880	ModbusTCP server connection status 8	ON: Client side has been connected OFF: Client side hasn’t been connected	R	×

SD label	Name	Content	R/W	Power-down save
SD2680	The first byte of the IP address	Local IP address	R/W	√
SD2681	The second byte of the ip address		R/W	√
SM2682	The third byte of the ip address		R/W	√
SD2683	The fourth byte of the ip address		R/W	√
SD2684	The first byte of subnet mask	Local subnet mask	R/W	√
SD2685	The second byte of subnet mask		R/W	√
SD2686	The third byte of subnet mask		R/W	√
SD2687	The fourth byte of subnet mask		R/W	√
SD2688	Default gateway first byte	Local default gateway	R/W	√
SD2689	Default gateway second byte		R/W	√
SD2690	Default gateway third byte		R/W	√
SD2691	Default gateway fourth byte		R/W	√
SD2692	The first byte of MAC address	Local MAC address	R/W	√
SD2693	The second byte of MAC address		R/W	√
SD2694	The third byte of MAC address		R/W	√
SD2695	The fourth byte of MAC address		R/W	√
SD2696	The fifth byte of MAC address		R/W	√
SD2697	The sixth byte of MAC address		R/W	√
SD2700	Communication speed display	0: 100Mbps/half duplex 1: 100Mbps/full duplex 2: 10Mbps/half duplex 3: 10Mbps/full duplex	R	×
SD2702	The modbusTCP server supports the maximum number of connections	Local modbusTCP server supports the maximum number of clients to make connections at the same time	R/W	×
SD2703	Modbus TCP connections	Local Modbus TCP connections	R	×
SD2710	Error code	Ethernet error code	R	×
SD2711	Socket ID of the error	-1: system default Modbus TCP server 0~5: Customer custom socket error	R	×
SD2720	Input the low bit of the number of ping request	External input ping command count	R	×
SD2721	Input the high bit of the number of ping request		R	×
SD2722	Input the low bit of the number of ping response	Number of replies after receiving external ping command	R	×
SD2723	Input the high bit of the number of ping response		R	×
SD2724	Output the low bit of the number of ping request	Send ping command count	R	×
SD2725	Output the high bit of the number of ping request		R	×
SD2726	Output the low order of the number of ping response	Number of replies after receiving sent ping command	R	×
SD2727	Output the high bit of the number of ping response		R	×
SD2728	Number of arp packets sent	Count of number of arp packets sent	R	×
SD2729	Number of arp packets received	Count of number of arp packets received	R	×
SD2730	Number of ip packets sent	Count of number of ip packets sent	R	×
SD2731	Number of ip packets received	Count of number of arp packets received	R	×
SD2732	Number of tcp packets sent	Count of number of tcp packets sent	R	×
SD2733	The number of tcp packets received	Count of number of tcp packets received	R	×
SD2734	Number of udp packets sent	Count of number of udp packets sent	R	×
SD2735	Number of udp packets received	Count of number of udp packets received	R	×
SD2740	Connection 1 local port number	Connection information and error information about the first Modbus TCP client’s connection to the PLC.	R	×
SD2741	Connection 1 IP address first byte		R	×
SD2742	Connection 1 IP address second byte		R	×
SD2743	Connection 1 IP address third byte		R	×
SD2744	Connection 1 IP address fourth byte		R	×
SD2745	Connection 1 peer port number		R	×
SD2746	Reserved		R	×
SD2747	Reserved
SD2748	Connection 1 error code		R	×
SD2749	Connection 1 error communication times low word		R	×
SD2750	Connection 1 error communication times high word		R	×
SD2760	Connection 2 local port number	Connection information and error information about the second Modbus TCP client’s connection to the PLC.	R	×
SD2761	Connection 2 IP address first byte		R	×
SD2762	Connection 2 IP address second byte		R	×
SD2763	Connection 2 IP address third byte		R	×
SD2764	Connection 2 IP address fourth byte		R	×
SD2765	Connection 2 peer port number		R	×
SD2766	Reserved		R	×
SD2767	Reserved
SD2768	Connection 2 error code		R	×
SD2769	Connection 2 error communication times low word		R	×
SD2770	Connection 2 error communication times high word		R	×
SD2780	Connection 3 local port number	Connection information and error information about the third Modbus TCP client’s connection to the PLC.	R	×
SD2781	Connection 3 IP address first byte		R	×
SD2782	Connection 3 IP address second byte		R	×
SD2783	Connection 3 IP address third byte		R	×
SD2784	Connection 3 IP address fourth byte		R	×
SD2785	Connection 3 peer port number		R	×
SD2786	Reserved		R	×
SD2787	Reserved
SD2788	Connection 3 error code		R	×
SD2789	Connection 3 error communication times low word		R	×
SD2780	Connection 3 error communication times high word		R	×
SD2800	Connection 4 local port number	Connection information and error information about the fourth Modbus TCP client’s connection to the PLC.	R	×
SD2801	Connection 4 IP address first byte		R	×
SD2802	Connection 4 IP address second byte		R	×
SD2803	Connection 4 IP address third byte		R	×
SD2804	Connection 4 IP address fourth byte		R	×
SD2805	Connection 4 peer port number		R	×
SD2806	Reserved		R	×
SD2807	Reserved
SD2808	Connection 4 error code	Error information about the fourth Modbus TCP client’s connection to the PLC.	R	×
SD2809	Connection 4 error communication times low word		R	×
SD2810	Connection 4 error communication times high word		R	×
SD2820	Connection 5 local port number	Connection information and error information about the fifth Modbus TCP client’s connection to the PLC.	R	×
SD2821	Connection 5 IP address first byte		R	×
SD2822	Connection 5 IP address second byte		R	×
SD2823	Connection 5 IP address third byte		R	×
SD2824	Connection 5 IP address fourth byte		R	×
SD2825	Connection 5 peer port number		R	×
SD2826	Reserved		R	×
SD2827	Reserved
SD2828	Connection 5 error code		R	×
SD2829	Connection 5 error communication times low word		R	×
SD2830	Connection 5 error communication times high word		R	×
SD2840	Connection 6 local port number	Connection information and error information about the sixth Modbus TCP client’s connection to the PLC.	R	×
SD2841	Connection 6 IP address first byte		R	×
SD2842	Connection 6 IP address second byte		R	×
SD2843	Connection 6 IP address third byte		R	×
SD2844	Connection 6 IP address fourth byte		R	×
SD2845	Connection 6 peer port number		R	×
SD2846	Reserved		R	×
SD2847	Reserved
SD2848	Connection 6 error code		R	×
SD2849	Connection 6 error communication times low word		R	×
SD2850	Connection 6 error communication times high word		R	×
SD2860	Connection 7 local port number	Connection information and error information about the seventh Modbus TCP client’s connection to the PLC.	R	×
SD2861	Connection 7 IP address first byte		R	×
SD2862	Connection 7 IP address second byte		R	×
SD2863	Connection 7 IP address third byte		R	×
SD2864	Connection 7 IP address fourth byte		R	×
SD2865	Connection 7 peer port number		R	×
SD2866	Reserved		R	×
SD2867	Reserved
SD2868	Connection 7 error code		R	×
SD2869	Connection 7 error communication times low word		R	×
SD2870	Connection 7 error communication times high word		R	×
SD2880	Connection 8 local port number	Connection information and error information about the eighth Modbus TCP client’s connection to the PLC.	R	×
SD2881	Connection 8 IP address first byte		R	×
SD2882	Connection 8 IP address second byte		R	×
SD2883	Connection 8 IP address third byte		R	×
SD2884	Connection 8 IP address fourth byte		R	×
SD2885	Connection 8 peer port number		R	×
SD2866	Reserved	Connection information and error information about the eighth Modbus TCP client’s connection to the PLC.
SD2867	Reserved		R	×
SD2888	Connection 8 error code		R	×
SD2889	Connection 8 error communication times low word		R	×
SD2890	Connection 8 error communication times high word		R	×

List of Ethernet Operation Error Codes

Error code	Description	Action	Processing approach	Test time
3680	Ethernet data reception error	Continue to run	Check whether there is any interference in the environment	When the command is executed
3681	Ethernet data reception timeout	Continue to run	Check if the network cable is loosened 1. Check whether the network peer is faulty, which results in failure in sending data. Check whether the network peer does not respond in time, which results in any delay in data. Under such circumstance, the reception timeout in the socket configuration can be increased.	When the command is executed
3684	Modbus TCP station number configuration error	Continue to run	Check slave station number setting. Check whether there is any problem with the receiving and sending mechanism of slave station.	When the command is executed
3685	Modbus TCP send buffer overflow	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
3686	Modbus TCP function code error	Continue to run	Check whether the set function code is a function code supported by PLC	When the command is executed
3687	Modbus TCP address error	Continue to run	Check whether the slave station has this address. (Please refer to Modbus exception 02).	When the command is executed
3688	Modbus TCP length error	Continue to run	Check whether the communication length exceeds the Modbus range	When the command is executed
3689	Modbus TCP data error	Continue to run	Check whether parameters of the command are wrong. Check whether the set value is supported by the slave station. (Please refer to Modbus exception 03).	When the command is executed
368A	Modbus TCP slave is busy	Continue to run	Message returned from slave station: Slave station is busy. (Please refer to Modbus exception 06).	When the command is executed
368B	Modbus TCP slave station does not support function code	Continue to run	Check whether this function code is supported by the slave station. (Please refer to Modbus exception 01).	When the command is executed
368C	Modbus TCP slave failure	Continue to run	Message returned from slave station: Slave station failed, please check whether slave station failed. (Please refer to Modbus exception 04).	When the command is executed
368D	Modbus TCP slave confirmation	Continue to run	Message returned from slave station: slave station confirmation. (Please refer to Modbus exception 05).	When the command is executed
368E	The current protocol of Modbus TCP does not support this command Instruction	Continue to run	The RS command cannot be used when the slave protocol is set, please change the protocol or close the contact before the RS command	When the command is executed
368F	Network port send timeout	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
3690	Receive buffer overflow	Continue to run	Check if the other device is sending data all the time	When the command is executed
36A0	Unavailable gateway for Modbus TCP	Continue to run	Message returned from the slave station: no available gateway. (Please refer to Modbus exception 0A).	When the command is executed
36A1	Modbus TCP indicates that no response was obtained from the target device. It usually means the device is not on the network.	Continue to run	Message returned from the slave station: The device is not in the network. (Please refer to Modbus exception 0B)	When the command is executed
36C0	ModbusTCP transaction identifier error	Continue to run	Check if there is network congestion and data can not be received in time.	When the command is executed
36C1	Modbus TCP server available links are full	Continue to run	Check if SD2702 and SD2703 have too many clients to link	When the command is executed
36C8	Insufficient space in the Ethernet stack	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
36C9	Number of connections exceeds the limit	Continue to run	Confirm whether the total number of connections exceeds the limit	When the command is executed
36CA	The last send is not completed	Continue to run	Use the sending completion sign to determine that the current sending is completed, and then send the next one	When the command is executed
36CB	TCP write exception	Continue to run	Use the sign bit device to judge whether the current connection status is normal. If it is not normal, no data transmission will be performed. For example, after the closing sign is set, data transmission will not be performed.	When the command is executed
36CC	TCP output exception	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
36CD	IP address is used	Continue to run	Please check if a connection exists with the same address information	When the command is executed
36CE	Error in server’s acceptance of connection	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
36CF	TCP receive buffer overflow	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
36D0	TCP link failed	Continue to run	It may be caused by opening the TCP client when the network cable is not connected.	When the command is executed
36D1	Exception when actively closing the connection	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
36D2	Abnormal shutdown occurred inside the protocol stack	Continue to run	May be shut down due to no answering for a long time. Check whether the peer is online and can ping.	When the command is executed
36D3	The peer initiates an RST link	Continue to run	1. Check whether the peer initiates abnormal shutdown. 2. As a client, the number of peer connections is full, or the peer port is not open.	When the command is executed
36D4	The protocol stack has a single-ended shutdown	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
36D5	There is an IP address conflict	Continue to run	The same IP device exists in the LAN, please change the IP address	When the command is executed
36D6	There is a MAC address conflict	Continue to run	The same MAC device exists in the LAN, please change the MAC address	When the command is executed
36D7	TCP send buffer overflow	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
36D8	UDP connection exception	Continue to run	IP address or port number may has been used.	When the command is executed
36D9	UDP send buffer overflow	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
36DA	Insufficient memory space when sending UDP	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
36DB	UDP send failed	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
36DC	UDP memory release failed	Continue to run	If this error message appears, please contact technical personnel	When the command is executed
36DD	UDP receive buffer overflow	Continue to run	The length of the data received by UDP exceeds the limit value of 512.	When the command is executed
4084	Data beyond the specified range is entered in the application command (for example, parameter 1 is specified as 0~1, setting 2)	Continue to run	Modify application command parameters	When the application command is executed
4085	The output result of the read application command exceeds the device range. (For example, the maximum output of the D device is D7999, but D8000 is used)	Continue to run	Modify application command parameters	When the application command is executed
4086	The output result of the write application command exceeds the device range. (For example, the maximum output of the D device is D7999, but D8000 is used)	Continue to run	Modify application command parameters	When the application command is executed
5080	The Ethernet socket has been linked and cannot be opened repeatedly.	Continue to run	Check if SOCOPEN command is executed repeatedly	When the application command is executed
5081	Ethernet socket is not open, which results in the failure in operation	Continue to run	Check whether set ON the connected sign bit of the SOCOPEN command (d2) parameter	When the application command is executed
5082	Socket ID input by Ethernet command is out of range.	Continue to run	Modify application command parameters	When the application command is executed
5083	Failed to create TCP server	Continue to run	Check if the connection is full	When the application command is executed
5084	Failed to create link	Continue to run	Check if the connection is full	When the application command is executed
5086	The socket ID used by the Ethernet command is not configured by the upper computer or is not enabled after configuration.	Continue to run	Check the Ethernet configuration of upper computer	When the application command is executed
5087	SOCRECV command reception timeout	Continue to run	1. Check if the network connection is normal. 2. Check whether there is data sent by the network peer.	When the application command is executed
5088	The SOCMTCP command specifies that the socket uses the configuration mode of a non-TCP client	Continue to run	Check the Ethernet configuration of upper computer	When the application command is executed
5089	When configuring the TCP server for the Ethernet socket, specify the local port as 502	Continue to run	Port 502 has been occupied internally, please modify the local port.	When the application command is executed
508A	The UDP port is specified as 1092	Continue to run	UDP port: 1092 is occupied by the system and cannot be used, please modify the local port number.	When the application command is executed
5090	Network cable connection exception	Continue to run	Check if the network cable is connected	When the application command is executed