User`s manual

Using the Scan Complete Bit

You can use the Scan Complete Bit (bit 8) in the Operation Status Register

of a switchbox to determine when a scanning cycle completes (no other bits

in the register apply to the switchbox). Bit 8 has a decimal value of 256 and

you can read it directly with the STAT:OPER? command (refer to the

STATe:OPERation[:EVENt]? command in Chapter 5 for an example).

When enabled by the STAT:OPER:ENAB 256 command, the Scan

Complete Bit will be reported as bit 7 of the Status Register. Use the GPIB

Serial Poll or the IEEE 488.2 Common Command *STB? to read the Status

Common Command to assert an GPIB Service Request (SRQ), you can

interrupt the controller when the Scan Complete Bit is set, after a scanning

cycle completes. This allows the controller to do other operations while the

scanning cycle is in progress.

The following example monitors bit 7 in the Status Register to determine

when the scanning cycle completes. The computer used in the example is

an HP Series 200/300 used with BASIC as the program language. The

computer interfaces with the mainframe over GPIB. The GPIB select code

is 7, the GPIB primary address is 09, and the GPIB secondary address is 14.

Example: Scan

Complete Interrupt

10 OUTPUT 70914;"*CLS" ! Clear all switchbox status

structure

20 OUTPUT 70914;"STAT:OPER:ENAB 256" ! Enable Scan Complete Bit to

set bit 7 in Status Register

30 OUTPUT 70914;"*SRE 128" ! Enable bit 7 of Status Register to

assert SRQ

40 OUTPUT 70914;"TRIG:SOUR EXT"

! Set to external trigger mode

50 OUTPUT 70914;"SCAN (@100:147)" ! Select channels to be scanned

60 OUTPUT 70914;"INIT"

! Start scanning cycle

70 WHILE NOT BIT(SPOLL(70914),7) ! Waiting for scan complete

80 PRINT "DO OTHER OPERATION HERE" ! Enter program lines for

computer to do other operations

90 END WHILE

100 PRINT "INTERRUPT GENERATED" ! Program goes to this line after

interrupt is generated by a

completed scanning cycle

110 END

38 Understanding the Agilent E1346A Multiplexer Chapter 4