Computer function symbol
A computer function is carried out in a separate computer rather than the DCS or PLC, for example an advanced control or optimisation calculation.
What the computer function symbol means
A computer function is carried out in a separate computer rather than the DCS or PLC, for example an advanced control or optimisation calculation.
How it is drawn
A hexagon.
The computer function symbol in each standard
Drawn as ISA 5.1 defines it, as on most US and international legends.
ISO 10628-2 does not cover instruments. On ISO-based P&IDs they are drawn as IEC 62424 PCE requests, or to ISA 5.1 on many international projects.
IEC 62424 has no separate symbol for this. Check the project legend.
German (DIN): Rechnerfunktion. See DIN P&ID symbols.
Where you see it on a P&ID
For advanced process control, calculations and data links to other systems.
Tag codes
The computer function is commonly tagged:
- FY
- UY
Tag formats follow the project numbering procedure. For instruments, the letters follow ISA 5.1, explained on the instrument symbols page.
Related symbols
Frequently asked questions
What does the computer function symbol look like on a P&ID?
A hexagon.
What is a computer function used for?
A computer function is carried out in a separate computer rather than the DCS or PLC, for example an advanced control or optimisation calculation. You will find it for advanced process control, calculations and data links to other systems.
What tag does a computer function have?
It is commonly tagged FY, UY. The exact tag format comes from the project numbering procedure and the legend sheets.
Is the computer function symbol the same in ISA and ISO?
ISO 10628-2 does not cover instruments. On ISO-based P&IDs they are drawn as IEC 62424 PCE requests, or to ISA 5.1 on many international projects. Companies vary the details, so always check the legend sheets at the front of the P&ID set.
What is the computer function called in German?
Rechnerfunktion. On a German R&I-Fließschema it is drawn to DIN EN ISO 10628-2 and DIN EN 62424.
- In production since 2014
- Thousands of daily users
- On MODEC FPSO projects since 2016