What does the nwkMaxFirstAttemptCSMABackoffs mean in NIB?

Hi James,

The MaxFirstAttemptCSMABackoffs has a valid range between 0 and 5. This attribute is defined in rti.h as 

By default, its value is 4.

#define RTI_SA_ITEM_MAX_FIRST_ATTEMPT_CSMA_BACKOFFS      RCN_NIB_NWK_MAX_FIRST_ATTEMPT_CSMA_BACKOFFS

If you want to modify this value, you can do something like:

rStatus_t status;
uint8 value8 = 5; //in this case we are changing the value from 4 (default) to 5
status =  RTI_WriteItemEx(RTI_PROFILE_RTI, RTI_SA_ITEM_MAX_FIRST_ATTEMPT_CSMA_BACKOFFS, 1, (uint8 *) &value8 ); //If status= RTI_SUCCESS = 0, then the operation was a success.

Take a look at the RemoTI API.pdf document. It is located in the Documents\API folder of your RemoTI installation directory. Section 3.4.2 (page 16) describes the State Attributes, including this one.

Hi Jose,

Thank you for your response.

I would like to know how it affects in the RF4CE environment.
For example, when the minimum value, what will be happend?

Hi James,

This parameter controls the maximum number of backoffs the MAC CSMA-CA algorithm will attempt before declaring a channel access failure for the first transmission attempt. Take a look at what the CSMA-CA algorithm does and that will answer your question.