Multi-link provides an economical and flexible solution that allows multiple human-machines to communicate with each other via RS485.In the operation of Multi-link, one human-machine works as a the master, the others work as the slave. Only the master can communicate with the PLC and receive data from it. And the slaves all receive data from the master. Therefore, every slave must have its own station number that allows the master to interact with it, which means interacting with the PLC.
Wecon hmi Muti-link settings:
Ⅰ.Connection Mode
An example of communication between a PLC and four human-machines is shown in the figure below. Note that human-machines usually communicate with each other via RS485 and every slave must have its own station number. When the system has just one slave, human-machines can also communicate with each other via RS232.
Ⅱ. Parameter settings of Multi-link Communication
Here are the operation procedures of setting communication parameters of Multi-link.
1.Select 【System Parameter】/【Connections and communication】, then select “add” in the screen. Select communication interface of Multi-link in the option of “communication interface” and “Multi-Link Protocol”in the option of “device type”.
2. Set the parameters of the master and the slave，the corresponding number and station number of the slave.
Notes:
The more slaves, the slower the communication speed may be.
The station numbers of the slave must be consecutive numbers starting from one without repeating.
The parameters of the master and the slave must be the same.
The order of the protocol must be the same when choosing the protocol of the master and the slave.
3.After setting the parameters above, select【Tool】/【Project Build】.Then you can download it to the human-machine.
Multi-Link Protocol settings:
Notes: If a system has one master and slaves, we should change the number of the slave in the option of master setting
and change the HMI station number in the option of slave setting. 
The station number of HMI increase by one, that is if the number of the slave is two, then the station number of the first slave is one and the second slave is two, etc. Other settings are the same as above.
Ⅲ. Notes
Please note the following points when using Multi-Link.
1. Please make sure that the projects of the master and the slaves are the same except the parameters of them.
2. The external address used in the scripts must be added to 【Project Configuration】/【System Parameter】/【Multi-Link Extra Address】when using scripts.
3. The interface parameters of the master and the slaves must be the same.
4. The order of the protocol must be the same when choosing the protocol of the master and the slaves.
5. The station numbers of the slaves must be consecutive numbers starting from one without repeating.
6. The more slaves, the slower the communication speed may be.
7. Suggest communicating via RS485 when selecting Multi-Link Protocol. When the system has just one slave, human-machines can also communicate with each other via RS232.
8. The external address used in the scripts must be added to 【Project Configuration】/【Multi-Link Data Area】.
