In AutoCAD Electrical the following block naming convention is used for schematic components:
- The first character is either "H" or "V" for horizontal or vertical wire insertion.
- The next two characters are reserved for family type (for example, PB for push buttons, CR for control relays, LS for limit switches). A zero (0) as the second character of the family type means that the symbol does not trigger a wire number change through it. (For example, T0 for terminals, W0 for cable markers, C0 for connectors.)
- The fourth character is generally a 1 or a 2: 2 for child contacts and 1 for everything else (parent or standalone component).
- If the symbol is a contact, then the fifth character is a 1 for normally open, 2 for normally closed.
- The remaining characters are not specified. They are used to keep names unique.
Most of the time if you create a custom schematic symbol and don't follow this naming convention there are not drastic consequences. For example, if you don't use "H" or "V" as the first character, AutoCAD Electrical may have to rotate a symbol if it is placed over a wire with the opposite orientation rather than use the symbol with that default orientation. The Toggle NO/NC command may not work if you don't use the 1 or 2 as the fourth character to indicate the contact type.
But, the rule "A zero (0) as the second character of the family type means that the symbol does not trigger a wire number change through it.", can produce very undesirable results if not followed. I recently had a customer report an issue that they could not insert destination arrows on a symbol. The symbol was a black box with multiple wire connections. They were able to insert a destination arrow on one connected wire but after that they would receive a message that the wire network already had a destination arrow.
After investigating I realized the symbol had a zero as the 3rd character in the block name. So, AutoCAD Electrical saw every wire connected to it as part of the same wire network and would not allow multiple destination arrows on one wire network. The fix was to resave the custom symbol with a block name following the naming convention and then using the Block Swap to update the existing drawings.
So be careful with that 3rd character when you name your custom blocks used for schematic symbols. Only use a zero if you intend it to be a pass-through component where all wires connected to it are seen as part of one wire network.
For more information see the Help topic, Overview of symbol naming conventions.
- Pat Murnen