How to configure packetizing control

Is there a way to force the radio modem RF packets to match the protocol packets sent to it? Yes, there are 3 commands that control how and when incoming data is packetized before transmitting over-the-air, RB, PK, and RO.

There are many situations where it is desirable that the protocol packets travel over-the-air in one contiguous block instead of being broken into smaller RF packets as would happen in the default mode of operation. Using the packetizing controls will add additional latency to the system but it will ensure that all of the protocol packets will be complete as either an entire packet will be received or the entire packet will be lost. There will be no partial packets to worry about.

Command descriptions and usage (RB, RO & PK):

Use X-CTU to set parameter values according to the following guidelines.

  • PK: The PK parameter sets the max RF data packet size. By default PK = 0x40 bytes (64 decimal). Its range is from 0 to 0x100 (0 to 256 decimal).
  • RB: The RB parameter specifies the number of bytes received into the DataIn buffer before RF transmission begins. By default RB = 1 byte, which means RF transmission begins immediately after 1 byte is received. Its range is from 1 to 0x100 (1 to 256 decimal). RB should be used in conjunction with the RO parameter.
  • RO: The RO parameter specifies the inter-character timeout before RF transmission begins. When a byte is received into the DataIn buffer the RO timer starts. The RO timer resets each time another byte is received into the DataIn buffer. If no other bytes are received before the RO timer expires, RF transmission will begin.
RO timeout is specified in 200 microsecond increments. The default is RO = 0x32 (50 decimal --> 10ms). RO = 0 means the timeout is disabled and no RF transmission will begin until RB bytes are received. The range is 0 to 0xFFFF (0 to 65535 decimal), which corresponds to 0 to 13.11 seconds.

If RO is nonzero the transmission will start when either RO times out or RB bytes are received.

More information on these parameters is available in the X-CTU software when the firmware version is selected on the Modem Configuration tab.

Please feel free to contact Digi Technical Services for assistance in choosing values for these parameters.

Key Words: packetize, packetization
Last updated: Aug 23, 2017

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