I recently learned this myself... >From the HAL manual section 1.1.4 net: "The direction indicator "<= and =>" is only to make it easier to read for humans and is not used by net."
HAL knows what can accept input and what can accept output and does what it needs to do automatically and will error if you try to make it do something it can't. >Len -----Original Message----- From: cmg...@sover.net [mailto:cmg...@sover.net] Sent: Monday, April 13, 2009 4:51 PM To: Enhanced Machine Controller (EMC) Cc: Enhanced Machine Controller @sover.net Subject: [Emc-users] HAL Direction arrow conventions As a new guy, I start my study of the HAL literature. Noting my questions, I thought to burden the group in a feeble jesture of participation ;-) this example quizzes me: To connect a signal to a pin we use the net command. halcmd: net X_vel <= siggen.0.cosine To see the effect of the net command, we show the signals again: halcmd: show sigignals: Type Value Name float 0.00000e+00 X_vel <== siggen.0.cosine When a signal is connected to one or more pins, the show command lists the pins immediately following the signal name. The "arrow" shows the direction of data flow - in this case, data flows from pin siggen.0.cosine to signal X_vel. Now let's connect the X_vel to the velocity input of a step pulse generator: halcmd: net X_vel => freqgen.0.velocity We can also connect up the Y axis signal Y_vel. It is intended to run from the sine output of the signal generator to the input of the second step pulse generator. The following command accomplishes in one line what two net commands accomplished for X_vel: halcmd: net Y_vel siggen.0.sine => freqgen.1.velocity [end of quote] Why no arrow between Y_vel and siggen? Also, the machine reply <== uses two =, is that significant? Perhaps additional study will explain it to me, but reading to this point has me wondering. TIA Cal ---------------------------------------------------------------------------- -- This SF.net email is sponsored by: High Quality Requirements in a Collaborative Environment. Download a free trial of Rational Requirements Composer Now! http://p.sf.net/sfu/www-ibm-com _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ This SF.net email is sponsored by: High Quality Requirements in a Collaborative Environment. Download a free trial of Rational Requirements Composer Now! http://p.sf.net/sfu/www-ibm-com _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
