Terminal Symbol: BUSW attribute
General
A horizontal discrete terminal symbol has a "connection rectangle". The rectangle has a "width" set to the "break length attribute" of the terminal. The rectangle "height" is defined in the BUSW attribute for the symbol.
A vertical discrete terminal's connection rectangle "height" is set to the "break length attribute" of the terminal. The rectangle "width" is defined in the BUSW attribute for the symbol.
Any wires entering the connection rectangle are considered to be connected to the terminal.
If a BUSW value is not supplied (the value is 0.0) then the dimension that can be set by the BUSW value is instead set to a default value that depends on the break length of the symbol.
For metric users, the default dimension will be set to 4.8mm for a terminal that has a break length smaller than 3mm and 8mm for a terminal with a break length 3mm and larger.
For imperial users, the default dimension will be set to 0.18" for a terminal that has break length smaller than 0.1125" and 0.3" for a terminal with a break length 0.1125" and larger.
The BUSW attribute is an "invisible constant" attribute. Because it is constant, it exists only as an attribute definition in the original symbol file, not as an editable attribute in each inserted symbol. You must edit the original symbol file to change the BUSW attribute.
To set the BUSW code for a terminal symbol
AutoCAD users:
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Open the symbol file in AutoCAD.
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Use the AutoCAD Properties command to alter the "BUSW" attribute definition.
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Set the DEFAULT attribute setting to the total height (top to bottom) of the connection box that you require for your terminal.
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Save the symbol.
PowerCAD users:
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Open the symbol file in PowerCAD.
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Use the PowerCAD ATTDEDIT command to alter the "BUSW" attribute definition.
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Set the DEFAULT attribute setting to the total height (top to bottom) of the connection box that you require for your terminal.
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Save the symbol.
Reversed polarised terminals
Polarised terminals have an orientation in the schematic drawing that is indicated in the connection reports. Since polarised terminals have an orientation, it is sometimes necessary to show a reversed polarised terminal. The indication that a terminal is reversed is contained within the terminal symbol, thus a specific symbol is required to represent a reversed polarised terminal.
To indicate that a symbol represents a reversed polarised terminal, add the letter 'R' following the number in the BUSW attribute.
For example:
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To represent a reversed polarised terminal that was 4mm high, the BUSW attribute would be set to the value "4R".
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To represent a reversed polarised terminal that was 1/8" high, the BUSW attribute would be set to the value "0.125R".
Note that the value "0R" or "0.0R" is not valid. The numeric part cannot be zero for a reversed polarised terminal.
A terminal symbol using RSTATUS that represents a reversed polarised terminal should have the value "RPOLAR" in the RSTATUS attribute. The value "FPOLAR" represents the forward orientation. The BUSW attribute does not control the orientation for polarised terminals using RSTATUS.
For a description of polarised terminals, see How to Report the Connection Side on a Terminal Strip (Ebase).