The Process Cache module can read and store data from Logix Controllers, DF1 Serial Interfaces, or Modbus devices which can later be uploaded to an historian or SQL database. The module has the capacity to store over 16 million records in its solid-state non-volatile memory. Each stored record includes a Date Time stamp with a 50ms resolution, the Tag Name, Data Type, and Value.
NOTE: Only the Process Cache Plus provides the user with the functionality to connect to the Aparian service which allows the stored data to be uploaded to an historian or SQL database. The Process Cache provides exactly the same logging functionality as the Process Cache Plus, but records can only be exported to Excel (via CSV files).
The process Cache could be used to log data at a remote site with limited communication with its base. It can be used to monitor OEM equipment at customer sites and the data uploaded when needed.
The Process Cache module could also be used to store records on mobile equipment such as trucks, drilling rigs, or snow ploughs. Once the equipment returns back to its base, the historical data can be uploaded and transferred to a more permanent storage. The module could also be configured to collect data and the data is only downloaded and examined if a fault occurs, otherwise the data is overwritten.
The Process Cache Module provides an extensive temporary on-board storage capability for storing process tags. A total of 16,777,216 records can be stored in the non-volatile memory. Each record consists of the following data:
|Date Time||UTC Time includes: Year, Month, Day, Hour, Minute, Second, Milliseconds. Time has a resolution of 50 milliseconds.|
|Tag Name||As defined in Controller for Logix or in Slate for other sources.|
|Data Type||BOOL, SINT, INT, DINT, or REAL|
The log index is managed by the module and incremented each time a new record is stored. The unload index is managed externally by the Upload Service and only incremented after a record was been logged successfully to the SQL Database, FT Historian, or text file. Both the Log Index and Unload Indices will loop around after reaching the end of the cache. The cache becomes 100% full when the log index catches up with the unload index. In this situation, either older records are overwritten (Log Mode = Overwrite) or newer records are not logged (Log Mode = Hold).
The Process Cache module is configured using the Aparian Slate application. This program can be downloaded from www.aparian.com free of charge. Slate offers various configuration methods, including a controller tag browser. Slate can also be used to monitor the modules status and used to download the historical data to a local file.
The module can operate in both a Logix "owned" and standalone mode. With a Logix connection the input and output assemblies will provide additional diagnostics information which will be available in the Logix controller environment.
The module uses isolated RS232 for DF1 communication providing better noise immunity. The RS232 port also uses a terminal block for convenient installation.
A built-in webserver provides detailed diagnostics of system configuration and operation, including the display of received DF1/Modbus/CIP communication packets, without the need for any additional software.