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The meaning of the "ConstOpen" parameter is different from the serial line. The TCP connection is established when the line is used for the first time and remains established (except for behavior in redundancy - see Operation of the line in redundancy).
If "ConstOpen" is checked for Line mode 1, when establishing a connection the KOM process waits for responses to all RFC2217 queries. If all responses are not received, the connection is closed.
If "ConstOpen" is unchecked for Line mode 1, when establishing a connection the KOM process does not wait for responses (except for the response to the initial WILL CPO, which detects RFC2217 support), so the connection will also work against servers that ignore some of the queries.
If "ConstOpen" is unchecked for Line mode 2, when establishing a connection the KOM process does not wait for the response to the initial WILL CPO, which detects RFC2217 support.
The following RFC2217 parameters are queried when establishing a connection:
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