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This IO Driver has the capabaility to record the timestamped event data sent by the ABB RTU's. The ABB RTU's can be configured to sent a "ERMI" message when a digital Input changes state. This "ERMI" message contains the IO address, Timestamp (millisec past the hour) & status of the event. The rest of this document describes the usage of this feature with the ProScada RP570 IO driver.
The RP570 Driver sends periodic time sync "TSI" messages to each connected RTU. The time sync period & an adjustable offset to account for propagation delays are adjustable parameters. The time of the Server PC is used. The user should configure a method of synchronising the PC to universal standard time.
Every time a "ERMI" message is received the timestamp is stored with the associated IO address, When ever the value of the IO point is read, this time stamp is sent back to the calling appilcation. If the IO address contains a Zero time stamp the driver generates one for NOW, this happens if the RTU only sends IDM messages on change of state but no ERMI messages have been received for this point.
Realtime Usage with the GE FIX Dynamics Scada
The timestamps are visible in the DI tags A_OPCTIME field (in some versions of FIX Dynamics this only displays 100ms accuracy). The best method with FIX is to use a Alarm History control which displays in Milliseconds. These features are not available in FIX32.
Realtime Usage with an OPC Client
The ABB timestamps are converted to FILETIME format & sent back to the OPC client. this means that when using OPC in asynchronous (callback) mode which most clients do, the OnDataChange calls will carry the remote timestamp from the RTU.
How valuble are millisecond timestamps flashing on a screen ?
The RP570 IO Driver has the capability to save the data from the "ERMI" messages to Local text (.CSV) files AND to an ODBC datasource. This allows the longterm storage of the data in a form that is easily queried Later by engineers using standard database tools (post mortem analysis).
This functionality is built into the IO driver at a low level, However the ODBC functions are MultThreaded so that problems with ODBC connection do not interfere with the normal functioning of the the Driver.
The format of the table in which the data is stored is predefined where the Primary key is time & sencondary key is IO address. The system integrator will normally supply a table that translates IO addresses to something more meaningfull before presentation to the customer.
This system has been tested with both MS Access & MS SQL Server however other databases should present no problems.
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