CHAPTER 3: MAINTENANCE AND TROUBLESHOOTING
SNAP PAC S-Series User’s Guide
39
Check Ethernet Errors
Next, use PAC Manager to check any Ethernet errors reported. These errors indicate network problems. You
will need to know the controller’s IP address.
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 controller. Click Status Read.
4.
Scroll down until you see the items Ethernet Errors: Late Collisions, Ethernet Errors: Excessive Collisions,
and Ethernet Errors: Others.
All three of these items should have a value of zero. If any of these items has a value other than zero, you may
have a network problem.
Analyze Communication Packets
If it appears that you have network problems, Opto 22 recommends using the open-source network protocol
analyzer (or “packet sniffer”) Wireshark (www.wireshark.org) to log and analyze network communication
packets on your network.
Have Your Network Certified
If you suspect network problems, you may need to have your network professionally certified. Opto 22 does
not offer network validation or certification services, but many network hardware manufacturers do. Contact
the manufacturer of your Ethernet network hardware to have them diagnose, fix, and certify your network.
If you continue to have problems communicating with the controller or I/O units after your network is
certified, contact Opto 22 Product Support. (See
TCP Settings
Retransmit timeout (RTO) refers to the length of time the controller waits while communicating before timing
out. The RTO is determined by the controller’s TCP/IP stack, and the stack continually recalculates the RTO
Ethernet Errors
