COE
IEC common-output element
Element with a double top line that produces one output depending on all elements of an array above it.
IEC
IEC · CCB
IEC common-control block
Notched block above an array; its inputs apply to every element below unless dependency notation limits them.
In plain English
What does IEC common-control block mean?
TI's overview of IEEE Std 91 describes the common-control block as the only distinctively shaped outline used in the IEC system. It sits above an array of elements, and an input to it is an input to every element below unless dependency notation states otherwise. Clocks, clears and enables of multi-bit registers are typically drawn here.
A simple example
When reading a register or latch symbol, start with the common-control block: it shows which signals act on all bits. The elements below then show only the per-bit data inputs and outputs, which keeps an octal device readable on one sheet.
What the drawings help you do
The block itself does not define a function; the labels and dependency numbers on its inputs do. Without those labels it is not possible to tell whether an input is a clock, an enable or a mode control.
This particular reference
Notched block above an array; its inputs apply to every element below unless dependency notation limits them. The common-output element has a double line and collects outputs below an array.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)
IEC · Notched block above an array of elements
Qualifying-symbol and dependency conventions as explained in TI's public overview of IEEE Std 91-1984, which incorporates IEC 617-12 work. Independent educational drawing; not certified IEC geometry or an IEC database identifier.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
Schematic · CCB
What it represents
TI's overview of IEEE Std 91 describes the common-control block as the only distinctively shaped outline used in the IEC system. It sits above an array of elements, and an input to it is an input to every element below unless dependency notation states otherwise. Clocks, clears and enables of multi-bit registers are typically drawn here.
When reading a register or latch symbol, start with the common-control block: it shows which signals act on all bits. The elements below then show only the per-bit data inputs and outputs, which keeps an octal device readable on one sheet.
The block itself does not define a function; the labels and dependency numbers on its inputs do. Without those labels it is not possible to tell whether an input is a clock, an enable or a mode control.
How to read it
- Read the control block first, then the per-bit elements.
- Dependency numbers decide which bits each control affects.
Information to show or reference
- Draw the notched shape distinct from ordinary elements.
- Label each control input with its function and dependency number.
- Show only per-bit signals on the elements below.
A distinction that matters
The common-output element has a double line and collects outputs below an array.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)
Describes the common-control block and how its inputs apply to the array.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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