Sony SRG-120DS Technical Manual page 28

If time out occurs on the controller, you can infer the lost message and state of the peripheral device by
retransmitting the message using the same sequence number. The following table shows the received message and
status by retransmission of the lost message, and the reference of correspondence after retransmission for each case.
(Except for the case that a time out occurs for reasons other than loss of message.)
Lost message
Command
Acknowledge message
Completion message for the
command
Inquiry
Reply message for the inquiry ERROR (Abnormality in the
Error message
Inquiry of the VISCA device
setting command
Reply message of the VISCA
device setting command
This unit has 2 sockets for the command to deal with advanced uses. When using VISCA over IP, up to 2
commands (including the current command) can be received. Depending on the message from the controller to the
peripheral device, there are some messages that do not need to guarantee delivery. However, the peripheral device
receives commands from multiple controllers while connected to VISCA over IP. If the multiple commands are sent
without waiting for the reply, the possibility of non-execution of the command and errors due to socket overflow
become high, because of limitations of order to receive commands or execution interval of command. It may reduce
the substantial efficiency.
Received message for
retransmission
Acknowledge message
ERROR (Abnormality in the
sequence number.)
ERROR (Abnormality in the
sequence number.)
Reply message
sequence number.)
Error message
Reply message of the VISCA
device setting command
ERROR (Abnormality in the
sequence number.)
Status after retransmission
Command is performed by
retransmission.
Command has been performed.
If only the Acknowledge
message is lost, the completion
message returns.
Command has been performed. If the result by the completion message is
Inquiry is performed by
retransmission.
Inquiry has been performed.
Command is not performed. If
the error cause eliminates,
normal reply is returned.
(Acknowledge, reply message).
Inquiry has been performed by
retransmission.
Inquiry has been performed.

Correspondence after retransmission
Continue processing.
If the result by the completion message is
needed, retransmit by updating the
sequence number.
needed, retransmit by updating the
sequence number.
Continue processing.
If the result by the reply message is needed,
retransmit by updating the sequence
number.
Eliminate the error cause. If normal reply
returns, continue processing.
Continue processing.
If the result by the reply message is needed,
retransmit by updating the sequence
number.