Issue
After running LANMON 3 on an I/NET C-LAN, it may return some error codes. The list below will help determine what they mean and the best way to address them.
Environment
- I/NET Controller LAN
- LANMON output text file
Cause
Controller LAN errors captured by the LANMON program.
Resolution
One of the most useful new features of LANMon 3.0 is the detection and labeling of several types of communications errors. The label associated with the detection of a communications error is stored in the disk file just in front of the communications packet to which the error label applies. The error labels are presented in ASCII text along side the hexadecimal data. This text should allow most I/NET technicians to perform some level of useful investigation into controller LAN communications problems and reduce the necessity for sending LANMon files in to Technical Service for analysis. The following paragraphs lists the error descriptions associated with the type of errors detected by LANMon. The Bold text represents the label you will see on the screen or in the capture file when LANMon detects that type of error.
ERR: Retry
This error indicates that LANMon has detected a retransmission of the same command. This is the most common error type and can be used to find which controllers are having problems receiving from others. You should reference the destination and source addresses listed in the retry packet and accumulate/record this information. If there is a prevalence of specific nodes (destination or source) showing up in the retry packets, this would serve as a significant pointer to examine for network problems in that physical area (possibly in the cabling, environmental disturbances, power, grounding, and controller hardware and/or application software)
ERR: LAN reconfiguration
This error indicates that LANMon detected the occurrence of a LAN reconfiguration. This is a normal expectation when a controller/node is added or removed from the network as a result of LAN cable disconnect or power. When intentional changes are not in-work on the network configuration, a LAN reconfiguration is typically the result of several sequential errors (typically retry’s) which prompts the sending controller/node to initiate a LAN reconfiguration on the basis that it appears a node has been lost and everyone needs to have a new picture of the network layout.
ERR: SDLC CRC Error
This error indicates that the LANMon Tap received an RS485 packet with incorrect CRC indicating the packet is corrupted in some way. This error results from data distortion on the cabling or from intermittent disruptions such as from EMI, noise or grounding fault. With this error, the primary address you are interested in is the source address. If you are seeing a number of CRC errors from the same node address, or a collection of node addresses, you may want to look for cabling or loading problems in that area, or the length of cable getting to the area. You should make note of where LANMon is positioned when seeing this error. The error could be expected to get worse as to get further away from the reporting node address. For this reason, it is often recommended that you perform LANMon captures and analysis from at least two points on the network and those points should be the two most distant ends of the network.
ERR: LAN master conflict with ##
This error indicates LANMon has detected a NULL command output from a controller/node other than the currently recorded LAN master. The ## number will show the address of the node currently understood to be the LAN master. The packet following this error message will contain the address of the contending LAN master. This master conflict error is frequently the result of multiple simultaneous LAN reconfigurations. There should only be one LAN master and it is the function of that one LAN master to output the NULL command each time the token makes one pass around to all the network addresses and arrives back at the LAN master.
The following error descriptions will be encountered far less frequently and are not typically used for LAN diagnosis.
ERR: Bad address
LANMon detected a destination or source address greater than 3F16 (6310)
ERR: Bad NULL
LANMon detected that NULL was sent out without the same destination and source address, or without the broadcast header.
ERR: Bad reconfigure
LANMon detected that reconfigure command “01” was sent out without the same destination and source address, or without the FF broadcast header.
ERR: Bad token
LANMon observed what appeared to be a token command but had byte count greater than 3, or had destination and source addresses the same.
ERR: Frame overrun
LANMon received >160 bytes on the Async port from the LANMon Tap which exceeds design limits/expectations.
ERR: Frame underrun
Async frame from LANMon Tap to PC was considered too short to contain any SDLC (CLAN) data.
ERR: Lost frame synch
The LANMon program running in the PC got out of synch with the data stream from the LANMon Tap. This should be an unusual error. If it is repeatedly encountered, You can try running the LANMon utility on a faster PC, or you can try running it with Monitor mode OFF. B E1 m N O
ERR: Bad frame CRC
The LANMon program detected a CRC error in the Async frame of data from the LANMon Tap. With the standard short (6 ft.) RS232 cable between the PC and Tap, this should be a very infrequent error.
ERR: Unknown error code
This is a catch-all error indication intended to present any error codes returned from the SDLC controller in the Tap that are not currently defined. You should not see this error message.
ERR: Frame too short
The Async frame of data from the Tap to the PC is considered too short to contain a valid SDLC packet.
