Model 7002Switch System Instruction Manual - Advanced Test ...

IEEE-488 Reference5.8.2 IFC (interface clear)The IFC command is sent by the controller to place the Model7002 in the local, talker, and listener idle states. The unitresponds to the IFC command by cancelling front panelTALK or LISTEN lights, if the instrument was previouslyplaced in one of those states.Note that this command does not affect the status of the instrument;settings, data, and event registers are not changed.To send the IFC command, the controller need only set theIFC line true for a minimum of 100µsec.Programming Example ⎯ Before demonstrating the IFCcommand, turn on the TALK indicator with the followingstatement:ENTER 707; A$At this point, the TALK light should be on. The IFC commandcan be sent by entering the following statement intothe computer:ABORTIO 7After the second statement is executed, the instrument’s frontpanel controls are locked out, including the LOCAL key.To restore front panel operation after asserting LLO, as in thefollowing example, enter:LOCAL 75.8.4 GTL (go to local) and localThe GTL command is used to take the instrument out of theremote state. Operation of the front panel keys is restored. IfLLO is in effect, the front panel LOCAL key will be disabledwhen the Model 7002 is put into remote. To cancel LLO, youmust set REN false.Programming Example ⎯ Place the instrument in the remotestate with the following statement:REMOTE 707Now send GTL with the following statement:LOCAL 707After the RETURN key is pressed, the TALK indicator turnsoff, indicating that the instrument has gone into the talkeridle state.Note that the instrument goes into the local state, and that operationof the front panel keys has now been restored (assumingthat LLO is not in effect).5.8.3 LLO (local lockout)The LLO command is used to prevent local operation of theinstrument. After the unit receives LLO, all its front panelcontrols except POWER are inoperative. In this state, pressingLOCAL will not restore control to the front panel.5.8.5 DCL (device clear)The DCL command may be used to clear the Model 7002and return it to a known state. Note that the DCL commandis not an addressed command, so all instruments equipped toimplement DCL will do so simultaneously.Programming Example ⎯ The LLO command is sent byentering the following statements:REMOTE 707LOCAL LOCKOUT 7When the Model 7002 receives a DCL command, it willclear the Input Buffer and Output Queue, cancel deferredcommands, and clear any command that prevents the processingof any other device command. A DCL will not affectinstrument settings, stored data, the channel list or scan list.5-30