SD (Scan Duration)
This command applies to the XBee/XBee-PRO S2C 802.15.4 RF Module.
Sets or displays the scan duration exponent.
Coordinator: If you set the ReassignPANID option on the coordinator (refer to A2 (Coordinator Association)), SD determines the length of time the coordinator scans channels to locate existing PANs. If you set the ReassignChannel option, SD determines how long the coordinator performs an Energy Scan to determine which channel it will operate on.
End Device: Duration of Active Scan during Association. In a Beacon system, set SD=BE of the coordinator. SD must be set at least to the highest BE parameter of any Beaconing Coordinator with which an end device or coordinator wants to discover.
Scan Time is measured as:
([# of channels to scan] * (2 ^SD) * 15.36 ms) + (38 ms * [# of channels to scan]) + 20 ms
Use the SC (Scan Channels) command to set the number of channels to scan.
SD influences the time the MAC listens for beacons or runs an energy scan on a given channel.
Example
The following table shows the results for a thirteen channel scan.
| SD setting | Time |
|---|---|
| 0 | 0.18 s |
| 2 | 0.74 s |
| 4 | 2.95 s |
| 6 | 11.80 s |
| 8 | 47.19 s |
| 10 | 3.15 min |
| 12 | 12.58 min |
| 14 | 50.33 min |
Parameter range
0 - 0x0F (exponent)
Default
4
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