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WIO Multicast


Component Version
Rocrail 2.1.2552+
WIOesp 559+
WIOpi 2.1.2552+


Per default WIO connects to the Rocrail server over TCP, which is a 1:1 connection.
WIO over UDP Multicast can be compared with CAN, in which every connected Node can read all the traffic and is loosely connected to a Rocrail Server.

This diagram shows the difference between the two communication methods:

With multicast communication it would be possible to react in Node X to an event from Node Y.
This can be established with IOScript.

Rocrail can process both communication types parallel, but WIO must be set to TCP or Multicast.
Every command/event/response packet has a NodeID in its header, and WIO Nodes will normally only process the one's addressed to it. NodeID zero is a broadcast which every node will evaluate.

With both communication types the commands and events will be acknowledged if a Rocrail Server is active.


  • Make sure all LAN components, like routers and switches, do support UDP Multicast.
  • Make sure the Router and the PC FireWall do not block UDP Multicast.
  • WIO does not lookup a Rocrail Server in case of Multicast.
  • When Rocrail Server runs on a Laptop, closing the lid will disrupt Multicast. Restart the Rocrail Server to re-establish Multicast.
  • Double check your IOScript concept to prevent endless loops between two or more WIO nodes.

Setup Rocrail

Both options:

  • Enable

must be enabled, and needs a Server restart.

The Multicast address MUST be set to which is also the default.
The ID can be left empty, and has no use in case of WIO RASCII.

Setup WIO

Serial Monitor

To enable Multicast:


To disable Multicast:


In both cases the WIO must be rebooted.

WIO Setup

Select the wanted Communication Type:

The WIO must be rebooted.


Activate Options4→R2RNet for Multicast or deactivate it for TCP.

The WIO must be rebooted.

wio/wio-multicast-en.txt · Last modified: 2024/01/04 07:36 by rjversluis