HDLC-Frame Protocol User's Guide (February 2004)

Using HDLC.FRAME Protocol
Request Specific Processing
Chapter 3 21
Request Specific Processing
Control Requests
All control writes to this protocol share a common format. The first four
bytes are defined as a header
Control Code Defines the action to be taken by this request.
Control Length The byte length of the data for this control request.
This data immediately follows the header.
Packet Length Some protocols allow packet data (data to be
transmitted over the wire) to be passed to a control
write following the control request data. For this
protocol, these two bytes must be zero because the
protocol does not allow packet data within a control
write.
This protocol supports the following Control Code:
5 CW_STATS Send IO_STATS status message
This control write triggers the protocol to send an
IO_STATS status message. For the format of this
message, see the section on “Status and Error
Messages”. The control length is zero.
Note that the protocol must have Control Write processing enabled, in
order to be able to process Control Write requests. See the “Terminal
Definitions” section of Chapter 4, Protocol Specific Configuration, for
details.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Control Code Control Length
Packet Length(0)