Grass Valley Switcher Products - Manual (Page 120)

120 Switcher Products — Protocols Manual
Section 4 — DPM CPL Protocol
Note See the points listed below:
• The switcher violates this utilization of the return ID.
• The switcher does not respond with Return Code messages even if the
return Id in the command sent by the DPM is nonzero.
• The switcher always responds to a Send Event On-line messages with
a Return Code message even if the return ID is zero. It inserts a zero
return ID into that Return Code message and sets the data value to
EID_ONLINE (= 15) instead of SUCCESS or FAILURE.
• The switcher does specify a nonzero return ID in its Send Event On-line
message and expects the DPM to echo that return ID in a Return Code
message, however the switcher ignores the data value.
Return Code
The Return Code message returns the result of a command. All commands
return an OK or ERROR status. A return code message is sent to a control
point only if the return ID field, in the message header, contains a non-zero
value.
As shown below, there is one field of data associated with the Return Code
message. This field contains the return code itself.
Also, the return ID sent with the command is returned in the message
header of the Return Code message. This is particularly important if a
control point is sending multiple commands and needs the return ID to
match a Return Code message to its command.
Note Refer to the note under Send Event above.
Table 113. Return Code Message Data
Field Size Value
Return code value 4 bytes
0 = OK / Success
0xFFFFFFFF =Error / Failure