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Siemens AG
Entry type: Application example Entry ID: 20983558, Entry date: 02/08/2016
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Master-Slave Communication via UDP Broadcast

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A master shall be able to send a data record to several slaves quickly and simultaneously to initiate a quasi-synchronous reaction. This requirement is particular frequent in conveyor and transport systems. The number of active slaves shall be flexible, and the function of the master be transferrable to other stations.

Solution
The application example realizes the task with SIMATIC S7-1200 and S7-1500 controllers, both interconnected via PROFINET. Any number of controllers can participate here.
 

Figure 1
 

The UDP protocol is used here for the communication. The advantage here is that the connections need not be configured statically, but can be set up and managed program-controlled. Hence, the participating stations need not be known to each other during the configuration process, and the master-slave switchover can be performed dynamically. This procedure enables the most flexible solution for expanding the system to almost any extend.

The following graphic shows the communication structure of the example program.
   

Figure 2
 
Advantages
  • Using already existing PROFINET/Industrial Ethernet infrastructures
  • Communication via internal PROFINET ports of the controllers without additional communication processors
  • Flexible topologies (simple extension and switchover of the master/slave function)

Documentation and Example Project
  Documentation (984,1 KB)
 Registrierung notwendig  Example project for STEP 7 V13 SP1 (8,6 MB)
 Registrierung notwendig  Library LBC for STEP 7 V13 SP1 (1,6 MB)


Last Changes
Limit of the broadcast to the master’s subnet
Recreating the application example for STEP 7 V13 SP1, S7-1200 and S7-1500


Additional Keywords
Multicast, Unicast, TUSEND, TURCV, transport, conveyor

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