The Ethernet Statistics window displays a number of diagnostic counters that are useful for monitoring Ethernet performance and troubleshooting problems. This window can be displayed using the following steps:
On the main RMCWin window's Window menu, click Ethernet Statistics. Notice that this command is only available for RMC modules with an ENET module.
Note: Using these diagnostic counters requires RMC ENET firmware version 20000915 or later. Also, reading these counters through RMCWin's TCP/IP driver requires RMC ENET firmware version 20010831 or later.
This list of counters is divided up into three logical groups to simplify understanding the values. However, all groups are read from the module and updated together. That is, refreshing the counters while displaying one group of counters also refreshes the other counters.
There are five buttons in this window:
Continuous Update checkbox
When this box is checked, the counters will be read from the RMC ENET continuously about four times per second. When this box is not checked, the counters are only updated when the Refresh button is clicked.
Refresh
Pressing this button will read all counters from the module. This operation takes place immediately and only happens once each time the button is pressed. This button is not available if the Continuous Update checkbox is checked.
Clear
Pressing this button will clear all counters in the module. This is often useful to see the affect of a change to the system. For example, suppose you change your controlling PLC's ladder logic and want to see its affect on the transfer rate. You may want to first start the ladder logic and then clear the statistics to avoid confusing old data with the new.
Save
Save all the current statistics data to a file.
Help
Display this topic in the online help.
Close
Close the Ethernet Statistics window.
Each counter is described below:
General
Note: Each of these counters is limited at 4,294,967,296, and if it reaches this value, then it will wrap back to zero and resume counting from there. This generally will only occur on the Total Bytes Received and Total Bytes Sent counters.
Total Bytes Received
This is the count of all bytes in all packets received by the RMC whether directed to either the RMC's MAC address or the broadcast MAC address (FF FF FF FF FF FF). Packets discarded due to the Rx Errors described below are excluded from this count, but all other packets are included, even if discarded for other reasons. NOTE: When this counter reaches 4,294,967,296, it will wrap back to zero.
Total Valid Directed Pkts Rcvd
This is the count of all packets received by the RMC that were directed to the RMC's MAC address, and were processed. This does not include packets received but discarded due to protocol errors such as invalid protocol, IP address, or destination TCP/UDP port.
Total Valid Broadcast Pkts Rcvd
This is the count of all packets received by the RMC that were directed to the broadcast MAC address, and were processed.
Total Discarded Directed Pkts
This is the count of all packets received by the RMC that were directed to the RMC's MAC address, but were discarded due to invalid protocol, IP address, or TCP/UDP port.
Total Discarded Broadcast Pkts
This is the count of all packets received by the RMC that were directed to the broadcast MAC address, but were discarded due to invalid protocol, IP address, or TCP/UDP port.
Total Bytes Sent
This is the count of bytes sent by the RMC over the Ethernet. NOTE: When this counter reaches 4,294,967,296, it will wrap back to zero.
Total Directed Pkts Sent
This is the count of packets the RMC sent to a specific MAC address. This is typically done by the RMC only in response to a request from another device.
Total Broadcast Pkts Sent
This is the count of packets the RMC sent to the broadcast MAC address. This is typically done only when the RMC is requesting a BOOTP or DHCP server to respond with its IP address.
CPU Load % (Last) (requires 20010831 or newer RMC ENET firmware)
This value gives the percent of CPU time that is currently being used. The closer this number approaches 100, the slower it will respond to incoming requests.
CPU Load % (Max) (requires 20010831 or newer RMC ENET firmware)
This value holds the maximum CPU load percentage that has been reached since the RMC ENET was started.
Rx Errors (Receive Errors)
Occasional occurrences of the following errors are expected. However, it is important to ensure that you do not get a lot of these errors. Also, if you are experiencing network instability, check these counters for clues to what might be going wrong.
Missed Packets (Ethernet Controller)
This is the count of packets missed because the Ethernet controller chip's internal buffer filled up temporarily.
Missed Packets (RMC ENET)
This is the count of packets missed because the RMC ENET's internal buffer filled up temporarily. This is differentiated from Missed Packets (Ethernet Controller) for internal troubleshooting purposes.
Runts Received
This is a count of all packets received under the 64-byte minimum specified by the Ethernet IEEE 802.3 specification. This indicates a problem in other devices on the network and could result in network performance problems.
Extra Data Received
This is a count of all packets received over the 1518-byte maximum specified by the Ethernet IEEE 802.3 specification. This indicates a problem in other devices on the network and could result in network performance problems.
Bad CRC Received
This is a count of all packets received with a problem with their Frame Check Sequence (FCS), which is a 32-bit Cyclic Redundancy Check (CRC). This could indicate electrical noise or an error in another device on the network.
Tx Errors (Transmit Errors)
Single Tx Collisions (20010608 RMC ENET firmware or older)
This counts the number of times the RMC ENET sent a packet, had a collision, but succeeded on the first retry. This retry happens within 500ms from the collision. High numbers of single collisions will degrade network performance. The simplest solutions are (1) reducing the number of devices on the network, and (2) using an Ethernet switch instead of an Ethernet hub to reduce the size of the collision domain.
In 20010724 RMC ENET firmware, this field was replaced by a collision histogram. See below.
Multiple Tx Collisions (20010608 RMC ENET firmware or older)
This counts the number of times the RMC ENET sent a packet and had more than one collision. Therefore, it took more than one retry to send the packet. The RMC's Ethernet controller will give up trying to send the packet after 16 attempts.
In 20010724 RMC ENET firmware, this field was replaced by a collision histogram. See below.
Tx Retries
This is the total of all transmit retries due to collisions. Therefore it is the sum of all the Single Tx Collisions and the retries for each Multiple Tx Collision. For example, suppose there were 32 single-collisions transmits, 2 two-collision transmits, and 1 three-collision transmits . The Single Tx Collisions counter would hold 32, the Multiple Tx Collisions counter would hold 3, and the Tx Retries counter would hold 39 ([32 x 1] + [2 x 2] + [1 x 3]).
Jabber
This counts the number of times the RMC ENET transmitter erroneously transmits for longer than 26 ms. This condition should never occur. This is a safeguard from having the RMC's Ethernet controller jam the network.
Underrun
This counts the number of times the RMC ENET was sending a packet but stopped in the middle. This should never occur.
Late Collisions
This indicates the number of times the RMC ENET detected a collision after the first 512 bits have been transmitted. A late collision may indicate an illegal network configuration such as too great a distance between hubs or devices.
Tx Collisions (nx) (requires 20010831 RMC ENET firmware or newer)
Each of these sixteen numbers gives the number of packets that had exactly that many collisions. For example, the "1 collision" entry includes counts all frames that had exactly one collision, not one or more. This can be used to determine the longest delay incurred because of collisions.
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