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Purpose of set auto_remove off

Hi all,

In one of the do files i found one command set auto_remove off .Can anyone pls explain what is the meaning and the usage of this command.While i tried this in specctra of Allegro 16.0,the below error is showing,why is this happening?Is there any alternate command to this?

# <<ERROR:>> Invalid option 'auto_remove' in 'set' command. Use 'set' to get list of available options

# <<ERROR:>> Syntax error in command: token 3 = off

# (content): set auto_remove off

# <<ERROR:>> Bad command not executed!

Thanks

Neha

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Jeff Underwood over 14 years ago

Specctra uses "sacrificial" behavior. During routing the algoritms work to make all connections while putting in many conflicts. After a number of passes of route the tool looks at those connections it has made that are causing the most conflicts; i.e. If the board has 0 unroutes after 5 passes and 2000 conflicts, it may "sacrifice" 20 of those connections to get the conflicts down to 1000. It will then try to reroute those 20 unconnects in future passes of route. Cadence has a few "undocumented" commands that were put in by developers early on for troubleshooting. "Set auto_remove on/off" is one of those undocumented commands. By turning auto remove off you are telling the router to NOT sacrifice any connections in order to reduce the number of conflicts. Therefore your 0 unroute board with 2000 conflicts will continue to stay 100% connected but the conflicts might actually increase as it tries to untangle the wiring to converge the board. Auto remove off can be a very effective command in Specctra and some designers swear by it. Give it a try and judge for yourself....
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Jeff Underwood over 14 years ago

Specctra uses "sacrificial" behavior. During routing the algoritms work to make all connections while putting in many conflicts. After a number of passes of route the tool looks at those connections it has made that are causing the most conflicts; i.e. If the board has 0 unroutes after 5 passes and 2000 conflicts, it may "sacrifice" 20 of those connections to get the conflicts down to 1000. It will then try to reroute those 20 unconnects in future passes of route. Cadence has a few "undocumented" commands that were put in by developers early on for troubleshooting. "Set auto_remove on/off" is one of those undocumented commands. By turning auto remove off you are telling the router to NOT sacrifice any connections in order to reduce the number of conflicts. Therefore your 0 unroute board with 2000 conflicts will continue to stay 100% connected but the conflicts might actually increase as it tries to untangle the wiring to converge the board. Auto remove off can be a very effective command in Specctra and some designers swear by it. Give it a try and judge for yourself....
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