The Issues menu reports on any bus errors or other issues that are occurring on the FC/SA bus the FIT is monitoring. The FIT is constantly monitoring the FC/SA bus for errors. Only the last five communication errors are reported in the issue menu and the FIT continues to update the number of issues during an MS/TP validation session. If the FIT is turned OFF, issue count and history are not maintained. For a list of common issues and corrective actions, see Figure 6. No MSTP displays when the FIT is connected to a Bus with a very poor Health Index.
|Potential Corrective Action
|Bad MS/TP frame. Invalid MS/TP header CRC or data CRC. Bad frames are typically caused by wiring issues, duplicate addresses, wrong baud rates and/or noise.
|Device came online. This is listed as an issue because a device came online after the last bus loop.
|Unless the controller was purposely removed from the bus or had its power turned off, determine why it came online late.
This could be caused by a problem with termination of 24 VAC power or bus cables.
Go to the controller in question and make sure all 24 VAC power and bus cables are securely terminated.
Note: If token passing is not occurring and is initiated with the FIT connected to a bus (ScanBus Menu is selected), Online Issues may result until all addresses participate in the token passing loop.
|Received character framing error. Character frames can also be caused by wiring issues, duplicate addresses, wrong baud rate or noise.
|MS/TP token was re-transmitted. A device handed off the token, but did not see any characters transmitted on the bus, so it re-transmitted the token.
|Device went offline. This device was online, received a PFM (Poll for Master) and did not reply to it.
|Same potential corrective actions as Online
|More than two devices with EOL switch ON. When the FIT is reading multiple bus segments (across repeaters) more than 2 EOL’s could be expected.
|If reading more than 2 EOL switch positions ON for a single bus segment, review switch positions of each controller on the bus segment to ensure only the actual controllers at the EOL are being used. See Proper EOL Termination for more information.
|A device on the bus talked Out of Sequence or attempted communication without the token.