# Network Connection Testing

Procedures in this section should always be conducted after the network connection is established. They may also be useful when symptoms indicate a network connection problem, or after recovering from such a problem.

The general network connection test procedure is performed from the Front Panel as follows:

1. Verify that Network Status LED is steady ON.
2. Enter PROGRAM mode.
3. Enter key code 914 N to get a list of active nodes on the network. If any nodes are missing, trouble-shoot using the common causes listed below.
4. Enter key code 902 N 4. This gets a list diagnostic codes for the last 10 network problems. To clear out old errors first, use 902 N 4**, wait a while, then re-issue the 902 N 4 command to get recent status and history.

Symptoms of a network connection problem are as follows:

- The Front Panel NET N LED configured for industrial network interface is BLINKING, indicating communications alarm.
- The networks alert message is delivered.
- All channels on a particular node are in communication alarm.
- Communications errors indicate time-outs, or no responses to polling requests.

The most common causes of a network connection problem are listed below:

- - Incorrect network port or cabling. Verify correct physical and electrical connections on both the RTU and network side of the connection.
- - If problems are isolated to only one of many nodes, suspect a problem local to that node. Examples include cable disconnection, power OFF, or a PLC fault. Other causes may be that the node has been taken out of run mode or commandeered by other activity on the net.
- - Unexpected heavy network usage may trigger time-outs on normally stable configurations. This may happen when one or more users of configuration software become active or increase their loading on the Net. The solution involves adjusting timers and parameters to handle the worst case loading.
- - Check MEM/DEF switch setting. Will impact required device configuration for the communications link.