After a positive response, the client should expect to see a status update from the Videohub
Server showing the status change. This is likely to be the same as the command that was sent,
but if the request could not be performed, or other changes were made simultaneously by
other clients, there may be more updates in the block, or more blocks. Simultaneous updates
could cancel each other out, leading to a response that is different to that expected.
In the absence of simultaneous updates, the dialog expected for a simple label change is
as follows:
OUTPUT LABELS:↵
6 new output label seven↵
↵
ACK↵
↵
OUTPUT LABELS:↵
6 new output label seven↵
↵
The asynchronous nature of the responses means that a client should never rely on the desired
update actually occurring and must simply watch for status updates from the Videohub Server
and use only these to update its local representation of the server state.
To lock a port, send an update to the port with the character “O” indicating that you wish to lock
the port for example:
SERIAL PORT LOCKS:↵
7 O↵
↵
ACK↵
↵
SERIAL PORT LOCKS:↵
7 O↵
↵
To forcibly unlock a port that has been locked by another client, send an update to the port with
the character “F” instead of using the usual unlock character “U”. For example, to override a
lock on port 7:
SERIAL PORT LOCKS:↵
7 F↵
↵
ACK↵
↵
SERIAL PORT LOCKS:↵
7 U↵
↵
Hardware status blocks can only be sent by the Videohub Server. If a client sends hardware
status blocks, they will be ignored.
81Developer Information
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