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Generating SRQ on buffer full

When your program must wait until the Model 2010 has completed an operation, it is more

efﬁcient to program the 2010 to assert the IEEE-488 SRQ line when it is ﬁnished, rather than

repeatedly serial polling the instrument. An IEEE-488 controller will typically address the

instrument to talk and then unaddress it each time it performs a serial poll. Repeated polling of

the Model 2010 will generally reduce its overall reading throughput. Therefore, use the srq%()

function call.

The Model 2010 provides a status bit for almost every operation it performs. It can be pro-

grammed to assert the IEEE-488 SRQ line whenever a status bit becomes true or false. The

IEEE-488 controller (your computer) can examine the state of the SRQ line without performing

a serial poll, thereby detecting when the 2010 has completed its task without interrupting it in

the process.

The following example program segment sets up the Model 2010 to assert SRQ when the

reading buffer has completely ﬁlled and then arms the reading buffer, initiates readings, and

waits for the Model 2010 to indicate that the buffer is full.

This is not a complete program. The commands to conﬁgure the trigger model and the reading

buffer (see the next example) are not shown. The example shown here can be modiﬁed for any

event in the Model 2010 status reporting system.

'Reset STATus subsystem (not affected by *RST)

CALL SEND(16, "stat:pres;*cls", status%)

CALL SEND(16, "stat:meas:enab 512", status%) 'enable BFL

CALL SEND(16, "*sre 1"' status%) 'enable MSB

CALL SEND(16, "trac:feed:cont next", status%)

'Start everything

CALL SEND(16, "init", status%)

WaitSRQ:

IF (NOT(srq%()) THEN GOTO WaitSRQ

CALL SPOLL(16, poll%, status%)

IF (poll% AND 64)=0 THEN GOTO WaitSRQ

After the program has detected an asserted SRQ line, it serial polls the Model 2010 to

determine if it is the device requesting service. This is necessary for two reasons:

• Serial polling the Model 2010 causes it to stop asserting the SRQ line.

• In test systems that have more than one IEEE-488 instrument programmed to assert

SRQ, your program must determine which instrument is actually requesting service.

Once an event register has caused a service request, it cannot cause another service request

until you clear it by reading it (in this case using STATus:MEASurement[:EVENt]?) or by

sending the *CLS command.

Example Programs C-5

Keithley 2010 User Manual

Other manuals for Keithley 2010