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*OPC? — Operation Complete Query Place a “1” in the output queue after all

pending operations are completed

Description

On power-up or when the *CLS or *RST is executed, the Model 2010 goes into the Operation

Complete Command Query Idle State (OQIS). In this state, no pending overlapped commands

exist. The Model 2010 has three overlapped commands:

• :INITiate

• :INITiate:CONTinuous ON

• *TRG

When you send the *OPC? command, the Model 2010 exits from OQIS and enters the

Operation Complete Command Query Active State (OQAS). In OQAS, the instrument

continuously monitors the No-Operation-Pending ﬂag. After the last pending overlapped

command is completed (No-Operation-Pending ﬂag set to true), an ASCII character “1” is

placed into the Output Queue, the Message Available (MAV) bit in the Status Byte sets, and the

instrument goes back into OQIS. Addressing the Model 2010 to talk sends the ASCII “1” to the

computer.

Note that the instrument always goes into OQAS when *OPC? is executed. If no pending

command operations are present (e.g., trigger model in idle state), the Model 2010 immediately

places an ASCII “1” in the Output Queue, sets the MAV bit, and returns to OQIS.

When used with the :INITiate or :INITiate:CONTinuous ON command, an ASCII “1” will

not be sent to the Output Queue and the MAV bit will not set until the Model 2010 goes back

into the idle state. The initiate operations are not considered ﬁnished until the instrument goes

into the idle state.

When used with the *TRG command, an ASCII “1” will not be placed into the Output Queue

and the MAV bit will not set until the operations associated with the *TRG command (and the

initiate command) are ﬁnished. The *TRG command is considered to be ﬁnished when the

Device Action completes or when operation stops at a control source to wait for an event.

To use *OPC? exclusively with the *TRG command, ﬁrst force the completion of the initiate

command so that only the *TRG command is pending. To do this, send the :ABORt command

to place the instrument in idle, which (by deﬁnition) completes the initiate command. Since

continuous initiation is on, operation continues on into the Trigger Model. After sending the

*TRG command, an ASCII “1” is placed in the Output Queue and the MAV bit sets when the

*TRG command is ﬁnished.

After *OPC? is executed, additional commands cannot be sent to the Model 2010 until the

pending overlapped commands are ﬁnished. For example, :INITiate:CONTinuous ON followed

by *OPC? locks up the instrument and requires a device clear (DCL or SDC) before it will

accept any more commands.

NOTE See *OPC, *TRG, and *WAI for more information.

4-40 Remote Operation

Keithley 2010 User Manual

Other manuals for Keithley 2010