User Guide

8.7 Moreaboutthe AddlevelParameter
The addlevel of the gates that have been fetched determines the manner
in which these gates are fetched into the schematic, and under what con
-
ditionsitcanbedeletedfromtheschematic.
Summary
Next: For all gates that should be fetched in sequence (e.g. the NAND
gates of a 7400). This is also a good option for devices with a single gate.
The ADD command first takes unused next-gates from components
whichexistonthecurrentsheetbefore“opening”anewcomponent.
Must: For gates which must be present if some other gate from the
component is present. Typical example: the coil of a relay. Must-gates
cannot be deleted before all the other gates from that component have
beendeleted.
Can: For gates which are only used as required. In a relay the contacts
may be defined with addlevel Can. In such a case the individual contacts
can be specifically fetched with INVOKE, and can later be deleted with
DELETE.
Always: For gates which as a general rule will be used in the schematic
as soon as the component is used at all. Example: contacts from a
multi-contact relay, of which a few are occasionally left unused. These
contacts can be removed with DELETE, provided that they were de
-
finedwithaddlevel Always.
Request: Only for components’ supply gates. The difference from Can
is that they are not counted in name allocation. So a device with a Next-
gateanda Request-gatewillnotbenamedIC1AandIC1B.
Relay:CoilandFirstContactmustbePlaced
A relay with three contacts is to be designed, of which typically only the
firstcontactwillbeused.
Define the coil and one contact as their own symbols. In the device, give
the coil and the first contact the addlevel Must. All the other contacts
aregiventheaddlevel Can.
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ComponentDesignExplainedthroughExamples