The <OpenCmd> and <CloseCmd> values follow the syntax precedented by UI-View Here's the gist of it:
The general form of an <OpenCmd> or <CloseCmd> is:
Output = Text to send to the TNC
Output allows/requires some character encoding via ^X or ^nnn to transmit control characters or decimal number (must be all three digits). For instance ^C is a control-C. ^255 transmits a byte whose value is 255. ^255^192^255 is one typical sequence to take some TNCs out of KISS mode.
By default, a <CR> (Carriage return, ^M or ^013) is appended to the end of the Output string. If you don't want this, put a ~ (tilde) at the end of Output to suppress the default <CR>.
To transmit a ^ (carat), you must put ^^ or ^094 (the ASCII value of a carat).
The Response specifies a string that APRSISCE/32 will watch for after the Output is sent. Any appearance of this string will allow APRSISCE/32 to continue on, regardless of the timeout. Reception of a specified Response or not doesn't change the delivery of the following commands. It may only allow those commands to go sooner rather than waiting for the full Delay.
Delay is specified in seconds and governs either how long APRSISCE/32 will wait for the Response string, or simply an enforced delay in the command stream.
At the time of this writing, Text is parsed but not used. Eventually it may be used to display missed responses, possibly only in the Port's Trace log as the commands are executed. Also, the @ is reserved for a future feature and therefore needs to be ^-coded.
If you don't specify a Response (no !), "cmd:" is expected.
If you don't specify a Delay (only one !), 1 second is assumed.
So, here's some sample commands:
<OpenCmd>~!!0</OpenCmd> <!— This is a simple NOOP (No Operation) — >