Abort Connection (CA) instruction

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Description (see instruction description format info here)

 

Function:Makes the DS abort the data connection with the network host, reset buffer overflow flags

 

Parameter (P) cmd format:PCA

 

Possible replies:A

 

Relevance conditions:---

 

First introduced:Earlier than "baseline" V3.14/V3.51

 

See also:Ethernet port and network communications, Establish Connection (CE) instruction

 


Details

 

Abort Connection instruction makes the DS end current data connection (if existed) and also resets routing buffers overflow flags (overflows are displayed by the status LEDs, overflow status also returned by the Echo (X) command- see S and E flags).

 

As a result of Abort Connection instruction execution UDP data "connections" are simply discarded. TCP data connections are reset (using RST packet).

 

Abort Connection instruction can be used at any time, even if the data connection is already closed and if the data connection was not established by the DS itself (i.e. it was a passive open).

 

OK (A) reply code is returned if command is accepted. This does not mean that the connection has been reset already, only that the DS has accepted the command. Actual connection status can be verified at any time using the Echo (X) command (see c flag).

 

Another instruction- Close Connection (CC)- can be used to properly shut down the TCP connection (using the FIN-ACK-FIN-ACK sequence). For UDP data "connections" there is no difference between the Abort Connection instruction and the Close Connection (CC) instruction.