HD9084 HDTV Caption Encoder Manual
Page 4-20 SERIAL CONTROL PROTOCOL
When multiple ports are permitted access to a particular data type, conflicts will be resolved on a “first
come, first served” basis. The caption encoder maintains a list of which ports are active for each data
type.
Normally, the various keyer commands (such as ^A2, ^A3, ^A6, ^A7) will set and clear the active status
automatically. To obtain maximum compatibility with existing software, these commands will exhibit the
following special behavior:
If a port does not have permission for the full field 1, but does have permission for the captions in field
1, then the command will not be denied, but will revert to the C1 form of the command.
For example, if Port A has permission for CF1 only, and a ^A3<cr> or ^A3 F1<cr> is issued, then
although Port A does not have permission for the full field 1, the command will not be rejected. Instead,
the command will be treated as though ^A3 C1<cr> had been sent.
4.6.1. Show Port Permission Maps
This command will report the permission map for each port. The permission map controls what data
types a port is allowed to become active in. (e.g., captions field 1, text field 2, XDS, etc.)
Command: ^AQ<cr>
Example result:
Permission Map
PORT A: C1 C2 T1 T2 XDS
PORT B: C1 C2 T1 T2 XDS
PORT C: C1 C2 T1 T2 XDS
PORT D: C1 C2 T1 T2 XDS OFFLINE
This example shows that all ports are permitted access to all data types (the factory default setting) and
the Port D modem is offline.
Permission Map
PORT A: C2 T1 T2 XDS
PORT B: C1 T1 T2 XDS
PORT C: C1 C2 T2 XDS
PORT D: C1 C2 T1 T2 ONLINE
This example shows that Port A is denied access to captions in field 1, Port B is denied access to
captions in field 2, Port C is denied access to text in field 1 and Port D is online and is denied access to
extended data services.
4.6.2. Alter Port Permission Maps
This command will alter the permission map for any port by adding or subtracting various data types.
Command: ^AQ<sp>pn<sp>-dt…dt…dt<cr>
Default: none
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