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can:higher_layer_protocols:duplicate_mac_id [2013/04/05 15:10] – heinzcan:higher_layer_protocols:duplicate_mac_id [2026/08/14 15:09] (current) – removed - external edit (Unknown date) 127.0.0.1
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-==== DeviceNet Duplicate MAC ID Protocol Summary ==== 
- 
-In the following explanation "Dup MAC Request/Response" means a Duplicate 
-MAC ID  Request/Response message at the same MAC ID as the node being described. 
- 
-=== Power-up === 
-  * Transmit Dup MAC request message 
-  * Wait 1 second (listening for replies - see ((During two 1-second timeout periods above)) below) 
-  * Transmit Dup MAC request message 
-  * Wait 1 second (listening for replies - see !1 below) 
-  * Transition to Online State 
- 
- 
-1a) If a Dup MAC request or response is received transition to the  Communication Fault state 
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-!2 - While in the Online state 
-2a) If a Dup MAC Request message is received, send Dup MAC Response 
-2b) If a Dup MAC Response message is received, transition to the  Communication  Fault state. 
-(this situation seems unlikely, but can occur if two network segments are powered up and then connected together) 
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- 
-There are two ways to leave the Communication Fault state: 
- 
-  - Manual Intervention (power cycle, device reset or other manual intervention) 
-  - MAC ID is changed (possibly to the same value) via the offline connection set which causes the device to re-start the media access state machine. This option is only available if the device supports the offline connection set. 
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-Generally speaking, if a duplicate MAC ID fault occurs, you must identify the node(s) with the incorrect MAC ID, make corrections, and cycle power on the network, or remove & reconnect specific devices, to bring the network up. 
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-If the affected devices support the offline connection set it is possible to change the MAC ID's and reset faulted devices from a configuration tool without cycling network power or disconnecting devices. 
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-This email is intended to be a general explanation, for complete, 100% accurate information please refer to Volume I, Chapter 4-7.3 and Chapter 6 in the DeviceNet specification. 
- 
-Nick Jones, Oct 15. 2002 
- 
- 
-http://odva.or.kr/devicenet_resources/DrDeviceNet/pc.htm 
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