6. LW3 Programmers’ Reference
HDMI20-OPTC series – User's Manual
44
6.2.7. Signature
DEFINITION: The signature is a four-digit-long hexadecimal value that can be optionally placed before
every command to keep a command and the corresponding responses together as a group.
Each line is terminated with a carriage return (Cr, ‘\r’) and line feed (Lf, ‘\n’) characters. In several cases the
number of the lines in the response cannot be determined in advance, e.g. the client intends to receive for the
whole response and also wants to be sure, that the received lines belong together and to the same command.
In these cases, a special feature the ‘signature’ can be used. The response to that particular command will
also be preceded by the signature, and the corresponding lines will be between brackets:
Ý
1700#GET /EDID.*
Ü
{1700
Ü
pr /EDID.EdidStatus=F89:E1;D1:E2;D1:E3;D1:E4;F89:E5
Ü
m- /EDID:copy
Ü
m- /EDID:delete
Ü
m- /EDID:reset
Ü
m- /EDID:switch
Ü
m- /EDID:switchAll
Ü
}
INFO: The lines of the signature are also Cr and Lf terminated.
6.2.8. Subscription
DEFINITION: Subscription to a node means that the user will get a notification if a property of the node
changes.
A user can subscribe to any node. These notifications are asynchronous messages and are useful to keep
the client application up to date, without having to periodically poll the node to detect a changed property.
When the user does not want to be informed about the changes anymore, he can simply unsubscribe from
the node.
ATTENTION!
The subscriptions are handled separately for connections. Hence, if the connection is
terminated all registered subscriptions are deleted. After reopening a connection all subscribe commands
have to be sent in order to get the notifications of the changes on that connection.
Subscribe to a Node
Ý
OPEN /MEDIA/VIDEO
Ü
o- /MEDIA/VIDEO
Get the Active Subscriptions
Ý
OPEN
Ü
o- /MEDIA/VIDEO
Ü
o- /EDID
Ü
o- /DISCOVERY
Subscribe to Multiple Nodes
Ý
OPEN /MEDIA/VIDEO/*
Ü
o- /MEDIA/VIDEO/*
Unsubscribe from a Node
Ý
CLOSE /MEDIA/VIDEO
Ü
c- /MEDIA/VIDEO
Unsubscribe from Multiple Nodes
Ý
CLOSE /MEDIA/VIDEO/*
Ü
c- /MEDIA/VIDEO/*
6.2.9. Notifications about the Changes of the Properties
When the value of a property is changed and the user is subscribed to the node, which the property belongs
to, an asynchronous notification is generated. This is notification is called as the ‘change message’. The
format of such a message is very similar to the response for the
GET
command:
Ü
CHG /EDID.EdidStatus=F48:E1
A Short Example of How to Use the Subscription
There are two independent users controlling the device through two independent connections (
Connection #1
and
Connection #2
). The events in the rows occur after each other.
Ý
OPEN /MEDIA/VIDEO/QUALITY
Ü
o- /MEDIA/VIDEO/QUALITY
Ý
GET /MEDIA/VIDEO/Quality.QualityMode
Ü
pm /MEDIA/VIDEO/QUALITY.QualityMode=graphic
Ý
GET /MEDIA/VIDEO/Quality.QualityMode
Ü
pm /MEDIA/VIDEO/QUALITY.QualityMode=graphic
Ý
SET /MEDIA/VIDEO/Quality.QualityMode=video
Ü
pw /MEDIA/VIDEO/QUALITY.QualityMode=video
Ü
CHG /MEDIA/VIDEO/QUALITY.QualityMode=video
Explanation: The first user (
Connection #1
) set a subscription to a node. Later the other user (
Connection #2
)
made a change, and thanks for the subscription, the first user got a notification about the change.
6.2.10. Legend for the Control Commands
Format
Description
<in>
Input port number
<out>
Output port number
<port>
Input or output port number
<loc>
Location number
<parameter>
Variable, which is defined and described in the
command
<expression>
Batched parameters: the underline means that
more expressions or parameters can be placed by
using a semicolon, e.g.
I2;I4;I5
or
F27:E1;F47:E2
Ý
Sent command
Ü
Received response
•
Space character
Connection #1
Connection #2
Connection #1
}
}
