ZLAN8303 is 3G/4G network solutions launched by Shanghai ZLAN after ZLAN8100. The serials contain 4 sub-models: 8303 (support Telecom 3G), 8343 (Support Modbus TCP Gateway), 8303-5 (Support Mobile and Unicom 3G/4G), 8303N (Support P2P). The function of Modbus TCP and P2P can add to models 8303 or 8303-5 such as ZLAN8343N-5.

8303 has RS232/485 interface, can send the data collected by RS232/485 to the cloud server. Combined with ZLAN P2P technology, the users can collect data anytime and anywhere without building server, the collecting method can also be a virtual serial port. If be 8343N, can convert Modbus TCP protocol to Modbus RTU, the users use Modbus TCP to collect data of RTU devices on the computer. ZLAN8343N and ZLAN8343N-5 are the most functional serial server separately applied to P2P Modbus Gateway of Telecom and Mobile/Unicom, suitable for PLC monitoring and field data collection very well.

8303 also has the Ethernet port, can use it to communication in the places with Ethernet, users can save the 3G/4G traffic. In addition 8303 can be used as 3G/4G router to achieve Ethernet port converting to 3G/4G.

Applications:PLC remote monitor, Industrial remote control/sensing/measurement, Public Utilities, Meteorological Data Acquisition, Three-Proofing & Hydrology Monitor, Finance, GPRS, etc.

The following is the application of each sub-model respectively.
1. Normal 3G/4G DTU

The normal 3G/4G DTU can be as TCP Server connected by other network devices, since the 8303 IP is not fixed when under 3G/4G mode, usually it isn’t as TCP Server, but mostly as TCP Client to connect an fixed IP (or domain name) Server, and send its collecting data. The software on Server ask data through polling style. The RS485/232 of 8303 can connect with serial device and PLC needed collected, sending polling command to PLC, and upload the returned data to server.

In this way the purpose of the 8303 IP must be set to the server IP, that is to say the user must lease a server with a public network IP. However, for some application users may not have a public network server, because the user dial-up through the router, then the router must be set on the "port mapping" and "dynamic domain name" to send 8303 data to the server. "Port mapping" and "dynamic domain name" have the following problems: 1) Some routers are standard telecom, cannot log in so cannot do some settings. 2) "Port mapping" for the average user may be too specialized, set up trouble. 3) "Dynamic domain name" free program may exist stability, real-time problems.
2. Multi-host and Modbus Gateway

The model with this function is ZLAN8343 or zlan8343-5. These two models have the following two functions: 1) Modbus Gateway can be configured. As long as set the “Device/Advanced Parameter/Transformation Protocol” to "Modbus TCP to RTU", it is switched to Modbus Gateway mode. The upper computer can be queried with Modbus TCP, while PLC can use RTU instructions. The Modbus of 8343 is storage Modbus Gateway, and the polling is more real-time. 2) Multiple hosts. When set to Modbus Gateway, multiple host queries can be made, and 8303 will answer separately to realize multi-host query. In the non-Modbus Gateway mode, for the 8343 model, you just check the "multi-host" support in more advanced options it can also implement the multi-host queries.

ZLAN-multi-host technology is a technology developed for multi-host monitoring a device at the same time. In the ordinary serial device server or DTU, when there is A, B two monitoring computer, A and B can send data to the device, but data the device received from the serial port will be sent to the A and B at the same time. In other words, when A and the device communicate, B will receive unwanted data, which will interfere B's communication. Many software protocols will not be able to adapt to this situation and may not work.

The ZLAN multi-host technology can achieve the communication scheduling between A and B computers. When A communicates with the device, the response data of the device is only sent to A; When B needs to communicate, you can quickly switch to B. ZLAN8343 will enable multiple computers to monitor the same device simultaneously.
3. P2P 3G/4G Serial Device Server

The model with this function is ZLAN8303N or ZLAN8303N-5. This model integrates ZLAN's P2P technology, which can solve the inconvenience of "Port Mapping" and "Dynamic Domain Name" in general 3G/4G DTU.

As shown in FIG. 2, compared with FIG. 1, (a) we increase the ZLAN P2P server, (b) the user computer replaces the monitoring server. Instead of using the server for monitoring, users can monitor their laptops whenever and wherever they are.

At the beginning of the communication, the P2P software on the user's computer---ZLVircom, communicated with the ZLAN P2P server. At the same time, 8303 can also communicate with ZLAN P2P server, which can establish direct communication between 8303 and ZLVircom (without the P2P server forwarding) after the negotiation is done. The software on the user's computer can communicate via a virtual serial port provided by ZLVircom or a TCP mock port.

When used, the user only needs to enter the serial number of 8303 that needs to be monitored in ZLVircom software to establish the P2P connection. The P2P approach allows users to get rid of the "Port Mapping", "Dynamic Domain Name" and the server of a public network IP, which can easily and conveniently do monitoring anytime and anywhere. The combination of P2P technology and 3G/4G wireless technology has implemented an innovative monitoring method.