RADIUS
Product
Description
PDR 121
iom_pdr121_04_r02.doc
Rev 02
Page 22 (67)
The Min and Max times allow one to configure different values at each site to totally avoid radio
collisions during instances of cascading events.
Note!
Many DNP3 RTU’s have internal collision avoidance mechanisms. Those must be
considered when configuring the PDR 121.
Note!
The re-transmission delay of the RTU’s must be adapted to the Collision Avoidance delays
of the RTU.
Example 1
Collision Avoidance Min = 1 s
Collision Avoidance Max = 3 s.
The radio will always wait 1 second plus a 0 to 2 seconds random time. (3-1 = 2 sec.)
The CA Delay time will be Min 1 second and Max 3 seconds.
This method can be used if one or more RTU’s have priority. The highest priority RTU’s
should be set to CA Delay Min = 0, (see example 2), and the lower priority ones to a higher
value.
Example 2
Collision Avoidance Min = 0 s
Collision Avoidance Max = 2 s
The radio will wait a random time between 0 and 2 seconds.
Example 3
Collision Avoidance Min = 3 s
Collision Avoidance Max = 0 s
The radio will always wait 3 seconds before transmission.
