CHAPTER 4: MAINTENANCE AND TROUBLESHOOTING
SNAP PAC Brains User’s Guide
31
31
TCP Settings
Retransmit timeout (RTO) refers to the length of time the brain waits while communicating before
timing out. The RTO is determined by the brain’s TCP/IP stack, and the stack continually recalculates
the RTO based on recent network traffic. If the network becomes busier, for example, the stack
automatically adjusts the RTO to a higher value.
If the TCP/IP stack times out while trying to transmit data, it doubles the current RTO and tries again.
This process continues for five retries; after that, the brain stops trying and sends a timeout message.
If you are receiving frequent timeout messages from the brain, you can change the TCP parameters
in PAC Manager.
1.
Choose Start
➞
Programs
➞
Opto 22
➞
PAC Project Software
➞
PAC Manager.
2.
In the PAC Manager main window, click the Inspect icon
.
3.
In the IP Address field, type the IP address of the brain. Click Status Write.
CAUTION:
Note the following recommended settings:
TCP Minimum Retransmission Timeout (msec):
250
TCP Initial Retransmission Timeout (msec):
3000
TCP Retransmission Attempts:
5
TCP Idle Session Timeout (msec):
240,000
