Grass Valley 2200 - Manual (Page 97)

5-7
Source Selection
If the DPM is reset or its switcher interface is reconÞgured, the sequence is:
1. The DPM sends out the message:
SEND_EVENT, event EID_ONLINE
This tells the switcher that the DPM just came on-line.
2. The switcher acknowledges receiving the on-line message by sending the
RETURN_CODE message:
(the message headerÕs return ID is set to 0)
val = EID_ONLINE (15).
then sends out a message cancelling all subscriptions:
UNSUBSCRIBE, CLEAR_SUBSCRIPTIONS
3. The switcher then takes over the initialization process with step 3 above.
Source Selection
There are multiple parts to the source selection part of the interface.
When the operator makes a selection on the aux row of the control panel (or via a
remote aux panel), the switcher sends a message to the DPM with the video
or key
source, never both. The switcher relies on the DPM's use of source memory to
select the appropriate key source. Essentially, the switcher is simply telling the
DPM that an operator pressed a button. It is up to the DPM to process this
information is an expected manner.
The switcher will send a selection for the front source, the back source or both
depending on the near/far selection made from the switcherÕs AUX BUS menu.
The following SET commands communicate this information to the DPM. These
messages include front/back information in the device ID Þeld. The channel bit is
set in the upper 16 bits. The lower 16 bits indicate if the front or back side is being
set (1 = back). These Þelds are deÞned as bit maps so that multiple channels may
be set at onece. However in practice, a source set command applies to only one
channel at a time.
PID_VIDEO_SOURCE
PID_KEY_SOURCE
NOTE: The switcher does not make aux bus selections as a direct result of an aux
row button press. If the DPM does not respond to the source message, the aux bus
output and aux row lamp indication will not change.
As an independent mechanism, the DPM sends messages with the video and key
sources, and the front/back status per channel. They are separate SET messages,
with the content of these parameters:
PID_FRONT_VIDEO_SOURCE_LIST (for 8 channels)
PID_BACK_VIDEO_SOURCE_LIST
PID_FRONT_KEY_SOURCE_LIST
PID_BACK_KEY_SOURCE_LIST
PID_FRONT_BACK_SELECT_LIST