Instrument I/O List is a document containing list of instrumentation which serve as an input or output of control system.
Therefore, only the tag number that physically has a cable which connects to the control system appears on I/O List.
When there are more than one control system in a plant (let say PCS and SIS), the I/O list shall clearly indicates which instruments is assigned to which control system or may separate them to different section in the document.
In I/O list, the following information should be stated but not limited to:
- Tag number
- Loop Number
- Service description
- P&ID Number
- Type of Instrument
- I/O Type
- Control System
- Range or set point
The information column in which I/O list contains may be as simple as above, however some project require I/O list to be detailed by having alarm list, controller action, logic “0”/“1”descriptor.
Later on, I/O list would include I/O number assignment (rack, slot, channel number) which information to be provided by control system vendor.
- Instrument Index
Filter all tag numbers that has an Input Output to make the I/O list
The purpose of I/O List
I/O list is used to determine the size of control system required by project, by counting how many I/O exists within a plant by each control system
Example of I/O list document shown in above image.