Chapter 4 Block ReferenceFieldPoint FP-3000 User Manual4-8 ©National Instruments CorporationTIME_STAMPThe time the alarm was detected by the FP-3000. In FOUNDATIONFieldbus, all devices share a common sense of time. This shared sense oftime is used to timestamp alarm conditions as they occur, rather than whenthey are reported.SUBCODEFor Block alarm, the subcode of the last error condition detected. TheBlock alarm, shared by all FOUNDATION Fieldbus function blocks in theFP-3000, is unique in that there are multiple conditions that can cause it togo active and clear. Any error condition reported in the BLOCK_ERRparameter of the block causes the block alarm to go active. The alarm doesnot clear until the last error condition in BLOCK_ERR has been resolved. Toindicate which error condition the BLOCK_ALM is reporting, the SUBCODEsubfield of the parameter is set to indicate the block error condition causingthe fault. If additional error conditions are detected, the SUBCODE andTIME_STAMP are updated to reflect the latest condition detected, but thealarm will not be reported a second time until every error condition hasbeen resolved.VALUEFor limit alarms, the value of the parameter causing the alarm condition(the Process Variable). For update events, the index of the modified staticparameter.Status and Mode Handling OverviewStatus and mode handling are crucial aspects of developing a distributedcontrol application. Mode refers to the mode of operation of a functionblock; allowable modes depend on the type of block, but generally includeOut of Service mode, Manual mode, and Auto mode.Status refers to the quality of a variable communicated between two blocks.When a block receives a variable with bad status, it can affect its currentmode of operation.Status HandlingParameters that can be communicated between blocks are composed of avalue and a status. The value is the data to be communicated, and the statusdescribes the quality of the data. When two blocks are logically connected