Mitsubishi Electric MELSEC Q Series User Manual page 195

(1) Setting method
For this setting, use the following functions in Setting/monitoring tools for the C Controller module.
<Q24DHCCPU-V/-VG>
•
Project view  "Parameter"  "CCPU Parameter"  <<User Ethernet port (CH1 and CH2) settings>>
<Q12DCCPU-V>
•
Project view  "Parameter"  "CCPU Parameter"  <<Built-in Ethernet port (CH1 and CH2) settings>>
(2) Precautions
(a) Checking by KeepAlive
When protocols are set in TCP, KeepAlive checks the status.
An existence check function is sent 22 seconds after the messaging reception of the last existence check
function from the external device to check for a response from the external device.
If there is no response, the existence check function is continuously sent at one second interval.
If a response cannot be confirmed within 8 seconds (30 seconds from the last messaging reception), the
connection is disconnected due to the lack of existence of the external device. (The connection will be
disconnected 30 seconds after the messaging reception of the last existence check function.)
The connection may also be disconnected if the target device is not compatible with the TCP KeepAlive
function (a response corresponding to the ACK function for KeepAlive).
(b) Resend processing for TCP connections
Resend processing for TCP connections when there is no ACK response of the TCP protocols from the
external device for sending in TCP connection, resend processing is performed at the following numbers of
resends and resend intervals.
Number of
12 times
resends
Interval until
(Number of resents x Number of resents x RTO
*2
resend
*1 : After 30 seconds from establishment of the connection, destination device error is assumed and the
connection is released even if the number of resends does not reach to 12 times.
*2 : The maximum resend interval is 60 seconds.
*3 : RTO (retransmission timeout) is a value that is increased exponentially based on RTT (round-trip time).
After the final resend, if there is no ACK response of the TCP protocol within 60 seconds, the connection will be
disconnected as an external device error.
(c) Connection not covered by the operation assurance
Operations of the following commercial connection devices are not assured. Customers need to confirm the
operation before using it.
• Connection using the Internet (a general public line)
• Connection using firewall devices
• Connection using broadband routers
• Connection using wireless LAN
*1
CHAPTER 12 FUNCTIONS ACCESSED VIA ETHERNET PORTS
*3
) / 1024 [Second]
12
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