# 3 Xbee s1 with 2 Arduinos Communication  Star Topology

**URL:** <https://forums.digi.com/t/3-xbee-s1-with-2-arduinos-communication-star-topology/15289>\
**Category:** XBee - 802.15.4\
**Tags:** arduino-xbee, series-1, xbee, zigbee\
**Created:** [August 18, 2015, 7:12pm UTC](https://forums.digi.com/t/3-xbee-s1-with-2-arduinos-communication-star-topology/15289 "2015-08-18T19:12:45Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![celalcan](https://avatars.discourse-cdn.com/v4/letter/c/a88e4f/32.png) [@celalcan](https://forums.digi.com/u/celalcan)\
**Post date:** [August 18, 2015, 7:12pm UTC](https://forums.digi.com/t/3-xbee-s1-with-2-arduinos-communication-star-topology/15289/1 "2015-08-18T19:12:45Z")

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i am using 3 XBee s1 802.15.4 and i have 2 arduinos (uno,mega)As you can see i am trying to build a star topology network in AT mode.I have one master and 2 slaves When i try to make peer to peer communication it works well but whenever i try to put the 3rd xbee i can not provide the communication  
Let me tell you what i did ;  
----to put the same PAN ID for each xbee in network  
----to set master as coordinator  
----to set the baud rate same for all(9600)  
----to set NODE ID of slaves as 1 and 2  
----to set RO Packetization Timeout 0  
----to set D7 disabled  
with those settings i can chat on XCT-U with all XBees without programme arduinos but when i try to put smthng to the arduino with xbee(slave) it doesnt work For instance whenever i try to begin the serial connection with arduino ( Serial.begin(9600); it destroys everything

i watched hundreds of tutorials and i couldnt make it

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**Author:** ![mvut](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/mvut/32/31_2.png) [@mvut](https://forums.digi.com/u/mvut)\
**Post date:** [August 24, 2015, 4:00pm UTC](https://forums.digi.com/t/3-xbee-s1-with-2-arduinos-communication-star-topology/15289/2 "2015-08-24T16:00:44Z")

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Most of your Arduino samples codes and tutorials are using the XBee ZB product and API mode. You need to either modify that code to use the API of the 802.15.4 modules or modify the code to just send over a COM port just like a cable is connected.