標準號：IS 12754 Pt.4-1989
發布日期：1990/2/1 12:00:00
實施日期：1999/12/31 12:00:00
適用范圍：The symbols established in this part of ISO 3511 have been developed to be used in conjunction with the symbols given in ISO 3511/1 and ISO 3511/2 and shall be considered as supplementary.They are intended to provide a means of illustrating process computer and/or shared display/control functions in the field of process measurement and control and may be used with the symbols of ISO 3511/1 and ISO 3511/2. They will enable users to show and identify in simple form the functions of instru-ments, the process computer, and shared display/control func-tions, or any combination of these.It is permissible to use the basic symbol for computer-based functions (see 3.1) throughout for any software-based digital system. This is not intended to preclude the use of the basic symbol for shared display/control functions (see 3.2) if the user considers this to be appropriate.The symbols are intentionally limited to identification on pro-cess flow diagrams, piping and instrument diagrams, etc. and do not provide means of illustrating specific instruments or parts thereof.The letter code for function identification shall be taken from table 1 of ISO 3511/1 and ISO 3511/2.The application methods are shown in the examples.