Glossary

The following terms are used in the I/O Driver Power Tool.

CSV File – A comma separated file that the I/O Driver Power Tool creates when it exports a configuration file. Comma separated files can be edited in any third-party application that supports CSV files, such as Microsoftâ Excelä or a text editor. Comma separated value files can also be created in a third-party application and read by the I/O Driver Power Tool.

Exception-Based Processing – SAC can perform exception-based processing on the following events:

  • The item’s data changes in common memory.
  • Asynchronous updates from the OPC server.
  • Operator actions.
  • Instructions from software applications.

I/O Address – A location in the process hardware (for example, a register, address, or point) that the driver reads from and writes data to. An I/O address is a portion of an OPC item.

I/O Driver – The software interface responsible for sending data to and acquiring data from the process hardware. When discussing OPC drivers the term I/O Server is sometimes used as well.

NODE:TAG.FIELD – A tagname in iFIX applications. It provides the information needed to access database data.

  • NODE: defines the computer where the data you require is located. This can be the computer you are working on or a remote computer.
  • TAG: is the name of a database block. Block names can be up to 30 characters long.
  • FIELD: defines the data type.

Process Database Block – Individual units of instructions that receive, verify, manipulate, and output process values. Process database blocks can also compare a process value against an alarm limit and perform calculations based on a specific process value.

Primary Database Blocks – Primary database blocks are blocks in the process database that communicate with field devices.

Prog ID – A vendor-specific string used to identify the OPC server.

Run-Time Configuration File – The process control software uses run-time configuration files (.OPC files) to communicate with the process hardware during run-time.

SAC – The Scan, Alarm, and Control program (SAC) is a iFIX system task that runs on a SCADA server. SAC transmits and receives data back and forth between the process database and the I/O driver’s common memory.

SAC performs the following tasks:

  • Fetches data from the I/O driver’s common memory.
  • Translates the data into the format expected by the process database.
  • Checks the data against the alarm limits and generates alarm messages.
  • Executes the control logic.
  • Detects exceptions.
  • Makes requested writes to the driver’s common memory.

Signal Conditioning – The method by which a raw process data value is scaled.

SIM Driver – An I/O driver used to simulate input and output of the process database for iFIX applications. SIM values are saved in the process database itself but are cleared when SAC is started or when you reload the process database. SIM registers range from 0 to 2000 for analog values and 0:0 to 2000:15 for digital values.

Time-Based Scan Time – With a time-based scan time, SAC retrieves data at set time intervals. Use time-based scanning when your data changes frequently.